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16 Ts Qoa mu OPEN-FILE REPORT 02-491, Version 1.0 Base from U.S. Geological Survey 7.5' Pinto Mountain quadrangle, 1986 Lambert conformal conic projection 1 0 1 MILE 1 2 1 KILOMETER 0 .5 1 CONTOUR INTERVAL 20 FEET SCALE 1:24,000 GN MN 14˚ by pervasively chalky-cemented sand and gravel. Deposits are inset into extant old and very old alluvial deposits (Qoa m1 ; Qvoa) Middle unit 1 (middle and early Pleistocene)—Sand and boulder gravel. Very well developed pavement with strongly varnished pebbles and cobbles. Prominent ridge-and-ravine (ballena) morphology; pavements extremely dark, deeply incised by dendritic network of ravines, and preserved only in discontinuous remnants along ridge crests. Moderately to well-cemented pedogenic K-horizon. Where pavement has been completely removed, erosional ridges are rounded and surface is littered with calcrete fragments. Pavement underlain by pedogenic Av horizon of very pale brown (10YR 7/3), loess-like, vesicular silt. Deposits debouch from channels incised into bedrock. Erosional morphology of unit exhibits three markedly different surficial settings, each providing a distinct microenvironment: (1) dark pavement as discontinous relics on ridge crests; (2) colluvial debris on ridge slopes, including lighter-colored young(?) slope wash derived from parent rock and dark-colored slope-wash (Qoc) shed from the varnished pavement surface; and (3) ravine-bottom alluvium Old colluvial deposits, undivided (Pleistocene)—Varnished debris aprons on recessive slopes below resistant cap rocks; varnished lag gravels. Colluvial debris also is shed from resistant quartzite and gneiss ridges down recessive granite slopes onto pediments and from flat-topped, pavemented surfaces of Qoa m1 and Qoa m2 down steep banks eroded into the underlying deposits. On older sedimentary deposits, colluvial deposits consist of lag gravels of varnished pebbles and cobbles. Debris aprons typically are dissected and partially eroded, leaving resistant flatirons of relict colluvium on slopes eroded into less resistant substrate. On slopes mantled with more than one generation of colluvium, flatirons of successively older deposits crop out progressively lower on slopes, providing a record of erosional retreat of capping unit. Well- developed pavements on colluvial deposits are very dark and smooth, consist of strongly varnished pebbles and cobbles, and are underlain by pedogenic Av horizon of very pale brown (10YR 7/3), loess-like, vesicular silt. Includes: Unit 2—Varnished debris aprons preserved in flatirons on slopes below cap rock Unit 1—Varnished debris aprons preserved in flatirons on slopes below cap rock VERY OLD SURFICIAL DEPOSITS—Deposits in alluvial fans and on piedmont slopes. Very old deposits exhibit strongly dissected geomorphic surfaces characterized by truncated Av/K soil profiles; carbonate morphology in K horizon is consistent with pedogenesis in the range of Stage IV-VI; pervasive hard to very hard chalky cementation is typically accompanied by abundant veins of laminar calcrete Very old alluvial deposits (early Pleistocene)—Moderately to well-cemented sand and boulder gravel; unit exhibits ridge-and-ravine (ballena) morphology. Ridges are rounded and littered with calcrete fragments; no remaining pavement. As mapped, may include quartzite-clast conglomerate unit (QTcq) QUATERNARY AND (OR) TERTIARY SURFICIAL DEPOSITS Conglomerate, quartzite-clast (Quaternary and (or) Tertiary)—Boulder conglomerate and sandstone shed in coarse alluvial apron from quartzite outcrops on Pinto Mountain Sedimentary deposits, undivided (Quaternary and (or) Tertiary)—Interpreted from aerial photographs. As mapped, may include parts of units Qvoa, Ts, QTcq, and (or) Tertiary saprolite COVER ROCKS Sedimentary strata of Pinto Basin (Pleistocene and (or) Pliocene)—Tilted sedimentary strata in Pinto Basin south of Pinto Wash. Outcrops of lake beds in center of basin are probably Pliocene; outcrops of arkosic sandstone just north of Hexie Mountains may be Pliocene or Pleistocene. Includes: Conglomerate beds—Boulder conglomerate forming coarse alluvial bed or beds derived from Proterozoic rocks in Hexie Mountains. In east-central Pinto Basin, conglomerate overlies and may interfinger with lacustrine deposits (QTpbl); proximal to Hexie Mountains, very similar boulder conglomerate mapped as old alluvial deposits, middle unit 1 (Qoa m1 ) overlies arkosic sandstone beds (QTpbs); Debris flow deposits—Matrix-supported sedimentary breccia containing cobble- sized clasts derived from Jurassic plutonic rocks in Pinto Mountains; overlies lacustrine beds (QTpbl) Sandstone beds—Reddened arkosic sandstone. Cross-bedded, coarse-grained sandstone containing scattered lenses of pebble conglomerate Lacustrine beds—Claystone and mudstone beds containing interbeds of siltstone and fine- to coarse-grained sandstone. Some sandstone beds are cemented with white calcite; includes at least one thin bed of fresh-water limestone Basalt (late and middle Miocene)—Basalt flows; olivine-bearing, massive, black. Microphenocrysts include euhedral laths of labradorite, euhedral olivine partially altered to iddingsite, and clinopyroxene. Occurs as two small exposures in northeastern corner of quadrangle and more extensively east of quadrangle in northern Eagle and southern Pinto Mountains. South of quadrangle, forms pipes and (or) near-vent flows on small inselbergs rising above pediment that forms south slope of Pinto Basin. Similar flows in Eagle Mountains southeast of quadrangle yield whole-rock conventional K-Ar ages of 7.8 and 10.2 Ma (Carter and others, 1987) Sedimentary deposits (late? and middle Miocene)—Arkosic sandstone and siltstone; minor conglomerate. As mapped, may include Tertiary weathering regolith. Restricted to single exposure in northeastern corner of quadrangle CRYSTALLINE BASEMENT ROCKS Dike rocks, undivided (Tertiary, Cretaceous, and (or) Jurassic)—Dacite porphyry, microdiorite, and quartz latite or rhyodacite dikes. Names are based on phenocryst percentages. Dacite dikes are gray hornblende-feldspar porphyry containing abundant to sparse phenocrysts of zoned euhedral plagioclase (labradorite to andesine) as large as 1 cm, subordinate euhedral brown hornblende and brown biotite, and rare embayed quartz set in a gray microcrystalline groundmass of plagioclase, alkali feldspar, quartz, sphene, apatite, and zircon. Dacite dikes trend northeast and are typically a few meters thick, several hundred meters long, and dip steeply. They form resistant ribs and exhibit dark brown patina of desert varnish. Similar dacite dikes intrude Cretaceous granodiorite and monzogranite in Eagle Mountains southeast of quadrangle. Microdiorite dikes are medium- to dark-greenish gray, fine- to very fine-grained, and composed primarily of hornblende and plagioclase; typically altered propylitically to epidote, chlorite, and calcite. Quartz latite dikes typically trend north and are light to medium gray, siliceous, aphanitic rocks containing microphenocrysts of quartz, microcline, plagioclase, and biotite. A quartz latite dike in Big Wash in east-central Eagle Mountains yields a zircon U-Pb intercept age of 145 Ma and a sphene U-Pb age of 142 Ma (James, 1989) Hypabyssal intrusive rocks (Tertiary, Cretaceous, or Jurassic)—Interpreted from color aerial photographs on basis of color and sheen similar to those of hypabyssal dike rocks (TJdu). Restricted to single locality north of Pinto Wash near west edge of quadrangle Granite of Pinto Wash (Late or Middle Jurassic)—Granite; pea-sized (2-5 mm) phenocrysts of quartz in fine- to medium-grained matrix of quartz and feldspar; leucocratic Quartz monzonite, monzogranite, and granodiorite of San Bernardino Wash (Middle Jurassic)—Ranges from diorite to granite; predominantly quartz monzonite, monzogranite, and granodiorite. Extensively exposed in eastern Pinto and southeast of quadrangle in northeastern Eagle Mountains (Index Map). Typically contains less than 25 percent quartz; porphyritic rocks are characterized by lavender-tinted phenocrysts of alkali feldspar. Mafic minerals consist of hornblende, biotite, and locally clinopyroxene; abundant sphene. Rocks show widespread propylitic alteration. Includes: 115˚ 52' 30" 34˚ 115˚ 45' 00" 34˚ 115˚ 45' 00" 33˚ 52' 30" 115˚ 52' 30" 33˚ 52' 30" Geology mapped by R.E. Powell, 1975-85; 1998-2000; structural point data collected by Powell and by R.A. Hope, 1964-69 (Hope, 1966) VERY YOUNG SURFICIAL DEPOSITS—Loose to slightly consolidated alluvial deposits in washes incised both into bedrock and into other Quaternary units and graded to base-level playa deposits in Chuckwalla Valley (Index Map). Geomorphic surfaces undissected to slightly dissected and characterized by active or recently active sediment accumulation Very young alluvial deposits, undivided (late Holocene)—Unconsolidated medium- to coarse-grained sand and sandy gravel, including subordinate fine sand and silt; bar and swale morphology; unvarnished clasts. Sparsely to moderately vegetated; prominent riparian shrub lines. Chiefly degradational. Includes: Very young alluvial deposits, Unit 2—White on color aerial photographs; no soil profile development. Mostly sand in washes developed on slopes flanking granite inselbergs. Transported and deposited in most recently active channels; inset into Qvya 1 and older deposits. Unit surfaces correlative with Q4b surfaces of Bull (1991) Very young alluvial deposits, Unit 1—Light gray (2.5YR 7/2) to pale yellow; gray on color aerial photographs; little or no soil profile development. Transported and deposited in channels or parts of channels less recently active than those in which unit Qvya 2 deposited; incised into young alluvial and older deposits. Unit surfaces correlative with Q4a and (or) Q4b surfaces of Bull (1991) VERY YOUNG AND (OR) YOUNG SURFICIAL DEPOSITS Very young and (or) young eolian deposits (Holocene)—Windblown sand, unconsolidated. Where it occurs in discontinuous surficial veneers, Qvyye is represented by a red-dot overlay pattern. As mapped, may include old eolian deposits Very young and (or) young playa deposits (Holocene)—Micaceous silt and clay containing minor sand and scattered granules and pebbles; very pale brown to pale brown. Light-colored surface on aerial photographs. Sparsely to moderately vegetated. Occurs in two small areas of ponded mudstone, one along Pinto Wash on east-central edge of quadrangle and one against low hills of uplifted strata of Pinto Basin south of Pinto Wash. Older parts of this unit overlain locally by windblown sand and distal fan deposits YOUNG SURFICIAL DEPOSITS—Loose to moderately consolidated alluvial and eolian deposits on piedmont slopes. Alluvial deposits exhibit slightly to strongly dissected geomorphic surfaces characterized by Av/Cox or Av/Bw/Cox soil profiles typical of Holocene surfaces (McFadden, 1988; Bull, 1991). Deposits form a thin mantle spread across landscape inherited from Pleistocene Young alluvial deposits, undivided (Holocene)—Loose to moderately consolidated alluvium deposited in canyon bottoms and on piedmont slopes. Fans spread out as aggradational aprons across inherited Pleistocene landscape, back-filled drainage washes from which they emanated, and grew progressively down- piedmont in nested complexes; oldest fans are proximal to range-front and youngest fans occur on lower piedmont. Successively younger fans are inset into older fans at their apices and either bury or feather out onto older fans distally. Abandoned surfaces are characterized by pedogenic Av horizon of loess-like, vesicular light brown (10YR 6/4) calcareous silt. Fan surfaces are not dissected by streams that originate on the surfaces. Piedmont alluvial deposits comprise two classes associated with geomorphically distinct piedmont settings: Class 1—Deposits forming alluvial aprons characterized by prominently cone-shaped, multi-lobed fans that coalesce into bajadas down- piedmont. Typically occur along bases of steep, fault-controlled mountain escarpments developed in resistant rocks having weathering and denudation characteristics that are relatively insensitive to climatic change (see Bull, 1991, p. 161-167). Class 2—Deposits that accumulated on broad piedmont slopes developed on less resistant rocks along deeply embayed mountain fronts. Weathering and denudation of these less resistant rocks are relatively sensitive to climatic change. Piedmonts are punctuated with inselbergs, rimmed with pediments, and exhibit broad, multi-faceted slopes that drain via small intra- piedmont valleys between slope facets. Alluvium on slope facets originates as fans distributed from feeder drainage-channels and as sheet wash on slopes between drainage channels. Fans in class 2 piedmont settings are characterized by low-convexity transverse profiles, and by surfaces having low-relief morphology. Fans and sheetwash on slopes between fans commonly merge imperceptibly. Down-piedmont, distributary slope drainage re-collects into intra-piedmont tributary valleys that, in turn, debouch onto fans farther down- piedmont. Deposits are formed by channelized flow and by unconfined overland flow in distributed network of branching and coalescing washes, fans, and thin slope-blanketing sheets. Young alluvial deposits are divided into old, middle, and young subunits roughly equivalent to Q3a,b,c units of Bull (1991). These units are further subdivided as needed. Consists of: Young alluvial deposits, young unit, undivided (late and (or) middle Holocene)—On class 1 piedmonts, unit shows pale brownish gray to pale gray on color aerial photographs; surfaces exhibit braided bar and swale morphology generated by anastomosing channels. Unconsolidated sand and gravel, poorly to moderately sorted; more sand and less gravel than older Qya units. Little or no desert varnish. Surfaces correlative with Q3c and (or) Q4b surfaces of Bull (1991). On class 2 piedmonts, unconsolidated sand and pebbly sand, poorly to moderately sorted. Proximally, deposits are inset into older Qya units; distally, they feather out onto surfaces of Qya m units. Surfaces correlated with Q3c surfaces of Bull (1991). Consists of: Young alluvial deposits, young unit, gravelly facies—Gravelly alluvium forming feeder-channel deposits in canyon-bottoms and fans proximal to steep range fronts. In Pinto Mountain quadrangle, fan deposits occur in class 1 piedmont setting Young alluvial deposits, young unit, sandy facies—Sandy alluvium forming valley-bottom deposits, fans and fan-skirts distal to steep range fronts on class 1 piedmonts, and alluvial-apron deposits on class 2 piedmonts deeply embayed into mountain fronts Young alluvial sand-skirt deposits (Holocene)—Distal sand deposits at toes of alluvial fans; at least in part reworked as windblown sand Young alluvial deposits, middle unit, undivided (middle Holocene)—On class 1 piedmonts, Qya mu forming gravelly proximal parts of fans is gray on color aerial photographs; gravelly and sandy medial parts are mottled gray and pale brownish gray; sandy distal parts are pale to medium brownish gray. Surfaces on gravelly parts of fans exhibit plumose bar and swale morphology; surfaces on sandy parts of fans exhibit braided bar and swale morphology generated by anastomosing channels. Unconsolidated to consolidated sand and gravel, poorly to moderately sorted. Moderate varnish on gravelly proximal parts of fans; swales exhibit pebbly pavements underlain by Av horizon. Surfaces correlative with Q3b surfaces of Bull (1991). On class 2 piedmonts, unconsolidated sand and gravel, poorly to moderately sorted. Surfaces tentatively correlated with Q3b surfaces of Bull (1991). Includes: Young alluvial deposits, middle unit, gravelly facies, undivided—Gravelly alluvium forming feeder-channel deposits in canyon-bottoms and fans proximal to steep range fronts. In Pinto Mountain quadrangle, fan deposits occur in class 1 piedmont setting. Locally, divided into: Young alluvial deposits, middle unit, gravelly facies 2—Younger gravelly alluvial deposits of middle unit; form fans that debouch from channels incised into older gravelly deposits of middle unit Young alluvial deposits, middle unit, gravelly facies 1—Older gravelly alluvial deposits of middle unit Young alluvial deposits, middle unit, sandy facies—Sandy alluvium forming valley-bottom deposits, fans and fan-skirts distal to steep range fronts on class 1 piedmonts, and alluvial-apron deposits on class 2 piedmonts deeply embayed into mountain fronts Porphyritic unit—Medium- to coarse-grained porphyritic plutonic rocks; vary in composition from quartz monzonite to monzogranite and granodiorite. Unfoliated to foliated. Hornblende-biotite to biotite-hornblende; phenocrysts are lavendar-tinted to pinkish-gray alkali feldspar; propylitically altered. Yields biotite conventional K-Ar age of 167 Ma (Bishop, 1963) in Pinto Mountains north of quadrangle and zircon U-Pb ages of about 165 Ma (Silver, 1978, oral communication; Wooden and others, 1994) in Pinto Mountains north of quadrangle and in Eagle Mountains southeast of quadrangle Mafic and intermediate intrusive suite, undivided (Jurassic)—Intermingled mafic and mafic intermediate rocks of varied composition and texture. Color index ranges from 50 to >95. Includes coarse- to very coarse-grained hornblendite and hornblende gabbro, medium- to coarse-grained biotite- hornblende diorite, fine-grained, dark-colored diorite to quartz diorite, medium- grained diorite and quartz diorite, and coarse- to extremely coarse-grained gabbro-dioritic pegmatite. Intruded by porphyritic quartz monzonite, monzogranite, and granodiorite of San Bernardino Wash (Jsbp). Includes: Dark unit—Especially dark-weathering mafic rock as interpreted on color aerial photographs. Restricted to southern margin of Pinto Mountains in quadrangle Gneiss assemblage of Hexie Mountains (Early Proterozoic)—Orthogneiss and paragneiss. Stratigraphic, and intrusive relations between constituent units typically overprinted by metamorphic and deformational events (Powell, 1993). Widespread in the Hexie, western Pinto, southeastern Eagle, Orocopia, Chuckwalla and Little Chuckwalla Mountains (Index Map). Consists of: Pinto Gneiss of Miller, 1938 (Early Proterozoic)—Intermingled ortho- and paragneiss. Widespread in the western Pinto, Hexie, Cottonwood, and Chuckwalla Mountains; also crops out in southwestern Eagle and easternmost Orocopia Mountains. Restricted to rocks included in Miller's original description of unit; does not incorporate expanded usage of Rogers (1961). Includes: Pinto Gneiss, leucocratic granitic orthogneiss—Foliated, lineated leucocratic biotite granite to granitic gneiss, medium- to very coarse-grained. Consists of alkali feldspar, plagioclase, quartz, and biotite; garnet is commonly present as isolated tiny crystals or as large, recrystallized clots of tiny garnets Pinto Gneiss, dark unit, undivided—From youngest to oldest, includes: (1) Biotite-quartz-feldspar gneiss; prominently layered, having alternating light- colored laminae rich in alkali feldspar and dark-colored laminae rich in biotite and oligoclase; contains abundant quartz (30-50%); garnet is common; (2) amphibolite; and (3) metasedimentary and (or) metamorphosed hydrothermally altered rocks. Includes: Metasedimentary and (or) metamorphosed hydrothermally altered rocks of Pinkham Canyon, undivided—Regionally, metasedimentary rocks comprise (a) schistose garnet-sillimanite/andalusite-muscovite-biotite-quartz- feldspar pelitic gneiss, (b) compositionally laminated, siliceous granofels consisting predominantly of quartz and cordierite and containing varying amounts of sillimanite and (or) andalusite, garnet, staurolite, plagioclase, and alkali feldspar, biotite, and muscovite, (c) bluish gray siliceous granofels, (d) scattered thin layers of ferromagnesian schist and granofels. Includes: Siliceous granofels of Wilson Canyon—Bluish gray siliceous granofels consisting predominantly of coarse-grained quartz and very fine-grained sericite that has replaced plagioclase and cordierite pseudomorphically Eagle Mountains assemblage (Proterozoic)—Regional grouping of metamorphic rock units comprising granitic basement terrane depositionally overlain by metasedimentary supracrustal section. Eagle Mountains assemblage is widespread in Eagle, Pinto, and Chuckwalla Mountains. Consists of: Metasedimentary rocks (Middle or Early Proterozoic)—Metamorphosed platform section of quartzite, pelitic schist and porphyroblastic granofels, ferriferous feldspathic schist, dolomite, and minor limestone. Not all rock types crop out in Pinto Mountain quadrangle. Thermally metamorphosed throughout region. Deformed in the Chuckwalla, Eagle, and southern Pinto Mountains; undeformed in central Pinto Mountains. Includes: Dolomite of Iron Chief mine (Middle or Early Proterozoic)—Very coarse- grained dolomite marble having interlocking recrystallized grains as large as 1 cm. White to light gray, grayish orange (10YR 7/4) to pale yellowish or orangish brown weathering. Thin to thick-layered intervals rich in dark-brown weathering siliceous nodules, pods, and lenses; sporadic layers of very coarse- grained white calcite marble (<3 m thick), quartzite, and dark-brown- weathering hematite-dolomite (iron ore). Contains scattered calc-silicate minerals, including garnet, diopside, and phlogopite Quartzite of Pinto Mountain (Middle or Early Proterozoic)—Consists of three interfingering lithofacies: (1) gray to bluish gray quartzite, coarse- to very coarse-grained, vitreous, thin bedded to massive, containing granule and pebble conglomerate beds; (2) white quartzite, coarse- to very coarse-grained, vitreous, massive; and (3) pelitic rocks. Includes two sequences of units, one designated by number and one by color and composition: Unit 9—White to light gray quartzite; chiefly interpreted from color aerial photographs Unit 8—Dark gray, coarse-grained, vitreous quartzite containing granule to pebble conglomerate beds; cross-bedded; upright Unit 7—Pelitic rocks; composed of andalusite, white mica, and quartz. Porphyroblastic to granoblastic; not foliated in Pinto Mountains; schistose in Eagle Mountains southeast of quadrangle. Well developed patina of desert varnish makes unit show as dark on color aerial photographs Unit 6—Very coarse-grained, vitreous, white to light-gray quartzite (98-99% quartz) with interlocking grains as large as 1 cm. As mapped, may include domains of remobilized quartz. Unit 5—Pelitic rocks; composed of andalusite, white mica, and quartz. Porphyroblastic to granoblastic; not foliated in Pinto Mountains; schistose in Eagle Mountains southeast of quadrangle. Well developed patina of desert varnish makes unit show as dark on color aerial photographs Unit 4—Dark gray, coarse-grained, vitreous quartzite with granule to pebble conglomerate beds; cross-bedded; upright Unit 3—Pelitic rocks; chiefly quartz-muscovite-sillimanite/andalusite rock. Porphyroblastic to granoblastic; not foliated in Pinto Mountains; schistose in Eagle Mountains southeast of quadrangle Unit 2—Very coarse-grained, vitreous, white to light-gray quartzite (98-99% quartz) with interlocking grains as large as 1 cm; grains are strongly recrystallized and have sutured boundaries; no evidence of relict rounded sedimentary grains; massive; bedding obscure or obliterated; thin seams rich in reddish black hematite and aluminosilicate minerals. As mapped, may include domains of remobilized quartz Unit 1—Mottled light- to dark-gray to bluish-gray quartzite (>95% quartz); medium bedded to massive; contains andalusite and sillimanite. Conglomerate occurs in layers and lenses as thick as 3 m near unconformity at base of quartzite unit. Clasts consist of pebbles and cobbles of (1) very coarse-grained white quartzite or quartz (85-95%), (2) tabular clasts of fine-grained black specular hematite-rich quartzite (5-15%), and (3) rare fine-grained jasper. Matrix is mottled light to dark gray quartzite. Deformed clasts have aspect ratios as great as 10:2:1. Hematite imparts characteristic rusty brown stain. Deposited nonconformably on regolith developed on granite of Joshua Tree Gray unit—Gray quartzite. On east flank of Pinto Mountain, chiefly interpreted from color aerial photographs. Consists of: Light gray unit—Light-gray to gray quartzite (>95% quartz). As mapped, may include domains of remobilized quartz Dark gray unit—Dark-gray to bluish-gray quartzite (> 95% quartz) White unit—Very coarse-grained, vitreous, white to light-gray quartzite (98-99% quartz) having interlocking grains as large as 1 cm; grains are strongly recrystallized and have sutured boundaries; no evidence of relict rounded sedimentary grains; massive; bedding obscure or obliterated. As mapped, may include domains of remobilized quartz. On east flank of Pinto Mountain, chiefly interpreted from color aerial photographs Pelitic unit—Dark metamorphosed pelitic rocks, containing very abundant aluminosilicate minerals; chiefly composed of quartz, muscovite, sillimanite and (or) andalusite; biotite-bearing in places. Porphyroblastic to granoblastic; schistose to unfoliated in Pinto Mountains. Unit also contains dark-colored quartzite; as mapped, may include bodies of Jurassic mafic and intermediate intrusive suite (Jmiu). On east flank of Pinto Mountain, chiefly interpreted from color aerial photographs. Well developed patina of desert varnish makes unit show as dark on color aerial photographs Metamorphosed regolith (Middle or Early Proterozoic)—Aluminous horizon at top of granite gneiss beneath overlying quartzite; 3 to 5 m thick. Consists of quartz (50-55%), muscovite, and as much as 40 percent andalusite and (or) sillimanite. Interpreted as metamorphosed weathering regolith. Feldspar phenocrysts in granite beneath regolith are increasingly altered upward toward contact (represented by increasingly abundant muscovite at the present metamorphic grade) and base of regolith is marked by abrupt disappearance of feldspar. Quartz grains have about same size range and distribution as phenocrysts in underlying granite gneiss. Metamorphosed regolith is porphyroblastic granofels here in Pinto Mountains, where it is caps porphyritic granite and is overlain by undeformed conglomerate. Schistose to southeast in Conejo Well quadrangle, where it overlies granite gneiss and underlies stretched-pebble conglomerate Granite gneiss of Joshua Tree (Early Proterozoic)—Biotite-plagioclase-quartz- alkali feldspar flaser augen gneiss. Light gray to white, leucocratic; light to moderate rusty brown patina on weathered surfaces. Augen are typically elongate, spindle-shaped aggregates of alkali feldspar, plagioclase, and quartz; some augen have cores of microcline megacrysts with "pressure shadow" tails of recrystallized finer-grained quartz and feldspar. Gneissic foliation exhibited as quartzo-feldspathic layers 1 to 2 cm thick separated by wispy, discontinous stringers of biotite. Folia typically are folded. Unit yields U-Pb zircon minimum age of 1650 Ma (L.T. Silver, 1978-1980, oral communication). Metamorphosed and penetratively deformed after development of weathering regolith and deposition of overlying quartzite of Pinto Mountain Porphyritic granite of Joshua Tree (Early Proterozoic)—Porphyritic granite. Light gray to white, leucocratic; light to moderate rusty brown patina on weathered surfaces. Phenocrysts of white to gray alkali feldspar and greenish- white plagioclase, and spheroidal quartz (<1 cm). Less than 10 percent biotite, typically in recrystallized clots. Unit yields U-Pb zircon minimum age of 1650 Ma (L.T. Silver, 1978-1980, oral communication) 1 N0TE: This geologic map is one representation of rock units contained in the digital database. The database also describes a hierarchical array of stratigraphic parents of the mapped units. The parent units aggregate the rock units shown on this map and can be used to generate and display more generalized geologic maps. Some of the parent units are described here in this Description of Map Units; all are described in the Description of Database Units in the summary pamphlet that accompanies this Open-File Report. REFERENCES CITED Bishop, C. C., compiler, 1963, Geologic map of California; Needles sheet: California Division of Mines and Geology, scale 1:250,000. Bull, W.B., 1991, Geomorphic responses to climatic change: New York, Oxford University Press, 326 p. Carter, J.N., Luyendyk, B.P., and Terres, R.R., 1987, Neogene clockwise tectonic rotation of the eastern Transverse Ranges, California, suggested by paleomagnetic vectors: Geological Society of America Bulletin, v. 98, p. 199- 206. Hope, R.A., 1966, Geology and structural setting of the eastern Transverse Ranges, southern California [Ph.D. thesis]: Los Angeles, University of California, 158 p. James, E.W., 1989, Southern extension of the Independence dike swarm of eastern California: Geology, v. 17, no. 7, p. 587-590. McFadden, L.D., 1988, Climatic influences on rates and processes of soil development in Quaternary deposits of southern California, in Reinhardt, J. and Sigleo, W.R., eds., Paleosols and weathering through geologic time: Principles and applications: Geological Society of America Special Paper 216, p. 153-177. Miller, W.J., 1938, Pre-Cambrian and associated rocks near Twenty-nine Palms, California: Geological Society of America Bulletin, v. 49, p. 417-446. Munsell Color, 1975, Munsell soil color charts, 1975 edition: Baltimore, Maryland, Macbeth Division of Kollmorgen Corporation. Powell, R.E., 1993, Balanced palinspastic reconstruction of pre-late Cenozoic paleogeology, southern California: Geologic and kinematic constraints on evolution of the San Andreas fault system, in Powell, R.E., Weldon, R.J., II, and Matti, J.C., eds., The San Andreas fault system: Displacement, palinspastic reconstruction, and geologic evolution: Geological Society of America Memoir 178, p. 1-106. Powell, R.E., 2001a, Geologic map and digital database of the Conejo Well 7.5 minute quadrangle, Riverside County, California, version 1.0: U.S. Geological Survey Open-File Report 01-31, 18 p., scale 1:24,000. http://geopubs.wr.usgs.gov/open-file/of01-31/ Powell, R.E., 2001b, Geologic map and digital database of the Porcupine Wash 7.5 minute quadrangle, Riverside County, California, version 1.0: U.S. Geological Survey Open-File Report 01-30, 18 p., scale 1:24,000. http://geopubs.wr.usgs.gov/open-file/of01-30/ Rogers, J.J.W., 1961, Igneous and metamorphic rocks of the western portion of Joshua Tree National Monument, Riverside and San Bernardino Counties, California: California Division of Mines Special Report 68, 26 p. Streckeisen A., 1976, To each plutonic rock its proper name: Earth Science Reviews, v. 12, p. 1-33. Wooden, J.L., Tosdal, R.M., Howard, K.A., Powell, R.E., Matti, J.C., and Barth, A.P., 1994, Mesozoic intrusive history of parts of the eastern Transverse Ranges, California: Preliminary U-Pb zircon results: Geological Society of America Abstracts with Programs, v. 26, n. 2, p. 10 4-105. Young alluvial deposits, old unit (Holocene)—Consolidated coarse gravel and sand forming fans adjacent to mountain-front escarpments. On color aerial photographs, unit shows as dark brownish gray to dark gray to black surfaces characterized by plumose anastomosing channels indicative of bar and swale morphology. Locally, unit includes cobbly and bouldery debris flow deposits. Moderate to strong varnish on rocky surfaces. Proximally, unit is inset into Pleistocene deposits (Qoa m3 ; Qoa y ); distally, it overlaps them. Inferred stratigraphic position, strong desert varnish, and bar and swale morphology suggest early Holocene age. Surfaces correlative with Q3a surfaces of Bull (1991). Extent of unit interpreted largely from aerial photographs. Includes: Young alluvial deposits, old unit, gravelly facies, undivided (middle and (or) early Holocene)—Gravelly alluvium forming feeder-channel deposits in canyon-bottoms and fan deposits proximal to steep range fronts on class 1 piedmonts. On some fans, two sequences can be distinguished morphologically. Locally, divided into: Young alluvial deposits, old unit, gravelly facies 2—Younger sequence of coarse gravelly alluvial deposits. At a few localities, early fan deposits can be distinguished in this sequence on the basis of a rougher surface texture as seen on color areal photographs. Locally, contains: Young alluvial deposits, old unit, gravelly facies 2, rough surface—Coarsest and most proximal parts of unit 2 that display an especially rough surface texture on aerial photographs; texture reflects high-relief bar and swale morphology associated with extremely coarse gravel or reworked debris Young alluvial deposits, old unit, gravelly facies 1—Older sequence of coarse gravelly alluvial deposits. At a few localities, early fan deposits can be distinguished in this sequence on the basis of a rougher surface texture as seen on color areal photographs. Locally, contains: Young alluvial deposits, old unit, gravelly facies 1, rough surface—Coarsest and most proximal parts of unit 1 that display a rough surface texture on aerial photographs; texture reflects high-relief bar and swale morphology associated with extremely coarse gravel or reworked debris YOUNG AND OLD(?) SURFICIAL DEPOSITS Young alluvial deposits, old oxidized sandy unit (middle and (or) early Holocene and late Pleistocene?)—Sand and pebbly to cobbly sand forming aprons on mountain-front and inselberg piedmonts where source terrane consists of Cretaceous granitic rocks. Thickest where buttressed against inselbergs or range-front; tapers down-piedmont into thin veneers on Pleistocene deposits. Where unit is exposed in arroyo walls high on piedmont slopes, loose surficial sediment passes down-section into firmer slope wash and alluvial deposits. Deposits of this unit redden with depth and probably contain one or more buried soil horizons. In places, reddened sediment contains scattered equant blebs of filamentous calcite, indicating an incipient (Stage I) calcic soil. Unit surfaces are smooth, sandy, and characterized by oxidized grains of potassium feldspar that range in color from reddish yellow (5YR 6/6 to 7/6) to yellowish red (5YR 5/6) to pink (5YR 7/4); appear orange on color aerial photographs. These grains occur as veneer underlain by pedogenic Av horizon of loess-like, vesicular very pale brown (10YR 7/3) calcareous silt, typically 1 to 4 cm thick. Av horizon underlain by pale-brown (10YR 6/3 to 6.5/3) to light yellowish-brown (10YR 6/4) sand. Unit inferred to include latest Pleistocene and (or) early to middle Holocene aggradational alluvial deposits as well as younger alluvial deposits that have accumulated as a result of sheet floods originating either as drainage basin discharge or as surface run-off across the older deposits. Proximal parts of unit are incised by channels in which more recent young (Qya m units and Qya y units) and very young (Qvya units) alluvial deposits have accumulated. Down-piedmont, where more recent young deposits feather out onto Qya os , Qya os surfaces are slightly dissected by anastomosing network of braided channels surrounding small islands of Qya os . Unit typically occurs as thin alluvial apron deposited on weathered granitic basement high on piedmont slopes and spread down-slope across older surficial deposits. As mapped, unit may include more recent young deposits YOUNG AND (OR) OLD SURFICIAL DEPOSITS Colluvial deposits, undivided (Quaternary)—Colluvial aprons shed from crystalline basement escarpments along canyon walls and range-fronts; predominantly talus OLD SURFICIAL DEPOSITS—Consolidated deposits in alluvial fans, on piedmont slopes, and in colluvial debris aprons. Old deposits exhibit slightly to strongly dissected geomorphic surfaces; gravelly deposits have well-developed and strongly varnished pavements; granitic debris characterized by Av/Bt/Bk/Cox soil profiles; Stage III-IV carbonate morphology. These deposits merge with one another to form a thin mantle that formed on an evolving Pleistocene landscape Old alluvial deposits (Holocene? and Pleistocene)—Consolidated alluvium deposited in canyon and arroyo bottoms and on piedmont slopes. As with young alluvial deposits (Qya units), old piedmont alluvial deposits comprise two classes: (1) Deposits that occur in alluvial aprons characterized by prominently cone-shaped, multi-lobed fans that coalesce into bajadas down- piedmont. Sediments generally have a source in resistant rocks having weathering and denudation characteristics that are relatively insensitive to climatic change (see Bull, 1991, p. 161-167). Sand and gravel. Unit surfaces consist of very well-developed pavements of strongly varnished pebbles and cobbles; dark and smooth. Pavements underlain by pedogenic Av horizon of very pale brown (10YR 7/3), loess-like, vesicular silt. Relict pavements and underlying old alluvial deposits are more deeply dissected with increasing age. (2) Deposits that occur on broad piedmont slopes developed on relatively less resistant rocks along deeply embayed mountain fronts. Weathering and denudation characteristics of these less resistant rocks are relatively sensitive to climatic change. In Pinto Mountain quadrangle, class 2 piedmont deposits consist of consolidated alluvium and slope wash that accumulated as thin aprons on pediments beveled onto Mesozoic granitic rocks, Proterozoic granite gneiss of Joshua Tree, and Quaternary and (or) Tertiary strata. The underlying crystalline rocks are exposed south of the quadrangle, where alluvial units are buttressed against bases of inselbergs in the Eagle Mountains (see Index Map). Much of mapping of these deposits is based on aerial photograph interpretation and has not been field-checked; age assignments are tentative. Consists of: Old alluvial deposits, young unit (Holocene? and late Pleistocene)—Sand and pebbly to cobbly sand deposited as alluvial fill in canyons and arroyos and in aprons buttressed against bases of inselbergs and mountain massifs. Deposits chiefly derived from exposures of granite gneiss of Joshua Tree and monzodiorite of Munsen Canyon south of quadrangle (see Powell, 2001a, 2001b). Pavements are light-colored, smooth, and moderately incised by dendritic networks of closely spaced gullies generated by surface run-off. Deposits partially bury older erosional landscape on which pediment flatirons had developed on earlier alluvial-slope aprons Deposits inset into Qoa m units. As mapped, may include older Qoa m units having atypically light-colored pavement Old alluvial deposits, middle unit, undivided (Pleistocene)—Sand and gravel. Surfaces consist of very well-developed pavements of strongly varnished pebbles and cobbles; surfaces are dark and smooth. Pavements underlain by pedogenic Av horizon of very pale brown (10YR 7/3), loess-like, vesicular silt. Relict pavements and underlying old alluvial deposits are more deeply dissected with increasing age. Includes: Middle unit 3 (late Pleistocene)—Sand and gravel. Pavements are generally continuous over broad relict surfaces; slightly to moderately incised by dendritic network of scattered to closely spaced gullies. Deposits are inset into extant old and very old alluvial deposits (Qoa m2 ; Qvoa) Middle unit 2 (middle? Pleistocene)—Sand and gravel. Pavements extremely dark; moderately to deeply incised by dendritic network of gullies. Pavement and Av horizon underlain by reddened pedogenic B-horizon, in turn underlain Qyau QTsu Qvoa Jmiu SURROUNDING 7.5' QUADRANGLES DESCRIPTION OF MAP UNITS 1 45 Strike and dip of flow bedding in sedimentary strata Inclined 49 Strike and dip of foliation and layering in metamorphic rocks Inclined Vertical Bearing and plunge of minor fold axis and parallel lineation Bearing and plunge of stretched-pebble lineation Bearing and plunge of aligned-mineral lineation 35 Qvya 2 Qvyye Qvya 1 Tb Jsbp CALIF AREA OF MAP Contact—Solid where location meets map accuracy standard (within 40 ft or 12 m); dashed where approximately located, may not meet map accuracy standard; dotted where concealed Facies boundary—Intra-unit boundary that separates alluvial deposits derived from different drainages. Approximately located, may not meet map accuracy standard Fault—High angle, observed or inferred. Solid where location meets map accuracy standard (within 40 ft or 12 m); dashed where approximately located, may not meet map accuracy standard; dotted where concealed Fault—Low angle, inferred. Approximately located, may not meet map accuracy standard Fault-line scarp Classification of plutonic rock types (from Streckeisen, 1976). A, alkali feldspar; P, plagioclase feldspar; Q, quartz. Quartz Syenite Quartz Monzonite Quartz Monzodiorite Syenite Monzonite Monzodiorite Granite Alkali-feldspar Granite Tonalite Diorite Syenogranite Granodiorite Monzogranite Quartz Diorite 90 65 35 10 5 20 60 Q Q A P 60 20 5 60 The matrix color of surficial materials and their pedogenic soils is classified according to the Munsell soil-color charts (Munsell, 1975). This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Pinto Mountain 7.5' Washington Wash Conejo Well (OF 01-31) New Dale San Bernardino Wash (OF 02-498) Fried Liver Wash Porcupine Wash (OF 01-30) Humbug Mtn. Twentynine Palms Mountain Ts Jmid Qcu Qya yu Qya mu Qya ms Qya yg Qya ys Qya mgu QTpbl QTpbs QTpbd Qoa m3 Qoa y Qya mg2 Unconformity Qya mg1 Qya og1 Qya ogu Qya os Qya og2r Qya og2 Qya og1r Qoa m1 Qyass TJh TJh QTcq Qoa m2 Alluvial deposits Unconformity (pediment) Unconformity (pediment) Unconformity (pediment) Qoa y CORRELATION OF MAP UNITS 1 Tb QTsu Qvoa Holocene Pleistocene CENOZOIC Pliocene Miocene TERTIARY QUATERNARY CRETACEOUS JURASSIC MESOZOIC Qoa m2 Qoa m1 Qya os Unconformity (pediment) Unconformity Jmiu Qvya 2 Qocu Qvyau Qvya 1 Qoa m3 Qyau Qoa mu PROTEROZOIC Plutonic rocks (Eastern belt) Surficial deposits Hypabyssal intrusive rocks and dikes Metamorphic rocks Colluvial deposits TJdu TJdu GEOLOGIC MAP AND DIGITAL DATABASE OF THE PINTO MOUNTAIN 7.5' QUADRANGLE, RIVERSIDE COUNTY, CALIFORNIA Prepared in cooperation with the NATIONAL PARK SERVICE and CALIFORNIA GEOLOGICAL SURVEY U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Qvyau Eolian deposits Wash deposits Qocu Playa deposits Qya mu Qya yu Qya yg Qya mgu Qoc 2 Qoc 1 Qya ms Relative age and stratigrapic relations uncertain Relative age and stratigraphic relations uncertain Jpw Qyass Qya ys Qya mg1 Qya ogu Qya og2 Qya og1 Qya mg2 Qya og1r Qya og2r Qoc 2 Qoc 1 Qcu Jsbp Unmetamorphosed cover Surficial deposits Surficial deposits Surficial deposits Crystalline basement QTcq Jmid QTpbc QTpbl QTpbc QTpbs QTpbd P A R K P I N T O M O U N T A I N S E A G L E M OUNTAI NS H E X I E M OUNTAI NS L ITTLE SAN BERNARDINO MOUN TAINS PINTO BA SI N C O X COMB MOUNTAINS C H U C K W ALLA VALLEY C HUCKWALLA MOUNTAI NS C HOCOLATE MOUNTAI NS O R O C OPI A MOUNTAI NS M O J A V E D E S E R T Dale Lake Salton Sea Hayfield Lake Palen Lake Red Butte Wash Ford Dry Lake Yucca Valley Joshua Tree Twentynine Palms Morongo Valley Palm Springs Indio Mecca Chiriaco Summit Desert Center Cottonwood Pass 116 ˚00' 115 ˚30' 116 ˚30' 115 ˚00' 34 ˚00' 33 ˚30' 0 5 10 km 0 5 10 mi 62 62 C O A C H ELLA VALLEY 10 Index Map Munsen Canyon Pinkham Big Wash Monument Mountain Pinto Mountain W ilson Canyon E A S T E R N T R A N S V E R S E R A N G E S S A L T O N T R O U G H LITTLE CHUCKWALLA MOUNTAINS C O L O R A D O D E S E R T Eagle Mountain Iron Chief mine X X X X Eagle Mountain mine X X Black Eagle mine Placer N A T I O N A L Pinto Wash J O S H U A T R E E C O T T O N W O O D M O U N T A IN S Canyon Wash N Pinto Mountain quadrangle Qvyye Qvyyp Qvyyp Jpw 28 Discontinuous Qvyye veneer on mapped unit Discontinuous Qvyye and Qocu veneers on mapped unit Discontinuous Qocu veneer on mapped unit SURFICIAL VENEERS Continuous Qya ms veneer on underlying Qya os unit 1 U.S. Geological Survey 904 W. Riverside Avenue, Room 202 Spokane, WA 99201 Version 1.0 by Robert E. Powell 1 Digital preparation by Pamela M. Cossette 1

SURFICIAL VENEERS - USGS · On slopes mantled with more than one generation of colluvium, flatirons of successively older deposits crop out progressively lower on slopes, providing

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Page 1: SURFICIAL VENEERS - USGS · On slopes mantled with more than one generation of colluvium, flatirons of successively older deposits crop out progressively lower on slopes, providing

16

Ts

Qoa

mu

OPE

N-F

ILE

RE

POR

T02

-491

, Ver

sion

1.0

Bas

e fr

om U

.S. G

eolo

gica

l Sur

vey

7.5'

Pin

to M

ount

ain

quad

rang

le, 1

986

Lam

bert

con

form

al c

onic

pro

ject

ion

10

1 M

ILE

1 2

1 K

ILO

ME

TE

R0

.51

CO

NT

OU

R I

NT

ER

VA

L 2

0 F

EE

T

SCA

LE

1:2

4,00

0

GN

MN

14˚

by p

erva

sive

ly c

halk

y-ce

men

ted

sand

and

gra

vel.

Dep

osits

are

ins

et i

nto

exta

nt

old

and

very

old

allu

vial

dep

osits

(Q

oam

1; Q

voa)

Mid

dle

unit

1 (

mid

dle

and

earl

y P

leis

toce

ne)—

Sand

and

bou

lder

gra

vel.

Ver

y w

ell

deve

lope

d pa

vem

ent

wit

h st

rong

ly

varn

ishe

d pe

bble

s an

d co

bble

s.

Prom

inen

t ri

dge-

and-

ravi

ne (

balle

na)

mor

phol

ogy;

pav

emen

ts e

xtre

mel

y da

rk,

deep

ly

inci

sed

by

dend

riti

c ne

twor

k of

ra

vine

s,

and

pres

erve

d on

ly

in

disc

onti

nuou

s re

mna

nts

alon

g ri

dge

cres

ts.

Mod

erat

ely

to w

ell-

cem

ente

d pe

doge

nic

K-h

oriz

on.

Whe

re

pave

men

t ha

s be

en

com

plet

ely

rem

oved

, er

osio

nal

ridg

es a

re r

ound

ed a

nd s

urfa

ce i

s lit

tere

d w

ith c

alcr

ete

frag

men

ts.

Pave

men

t un

derl

ain

by p

edog

enic

Av

hori

zon

of v

ery

pale

bro

wn

(10Y

R 7

/3),

lo

ess-

like,

ves

icul

ar s

ilt. D

epos

its d

ebou

ch f

rom

cha

nnel

s in

cise

d in

to b

edro

ck.

Ero

sion

al m

orph

olog

y of

uni

t ex

hibi

ts t

hree

mar

kedl

y di

ffer

ent

surf

icia

l se

tting

s, e

ach

prov

idin

g a

dist

inct

mic

roen

viro

nmen

t: (1

) da

rk p

avem

ent

as

disc

onti

nous

rel

ics

on r

idge

cre

sts;

(2)

col

luvi

al d

ebri

s on

rid

ge s

lope

s,

incl

udin

g lig

hter

-col

ored

you

ng(?

) sl

ope

was

h de

rive

d fr

om p

aren

t ro

ck a

nd

dark

-col

ored

slo

pe-w

ash

( Qoc

) sh

ed f

rom

the

var

nish

ed p

avem

ent

surf

ace;

and

(3

) ra

vine

-bot

tom

allu

vium

Old

col

luvi

al d

epos

its,

und

ivid

ed (

Ple

isto

cene

)—V

arni

shed

deb

ris

apro

ns o

n re

cess

ive

slop

es b

elow

res

ista

nt c

ap r

ocks

; va

rnis

hed

lag

grav

els.

Col

luvi

al

debr

is a

lso

is s

hed

from

res

ista

nt q

uart

zite

and

gne

iss

ridg

es d

own

rece

ssiv

e gr

anite

slo

pes

onto

ped

imen

ts a

nd f

rom

fla

t-to

pped

, pa

vem

ente

d su

rfac

es o

f Q

oam

1 an

d Q

oam

2 do

wn

stee

p ba

nks

erod

ed i

nto

the

unde

rlyi

ng d

epos

its.

On

olde

r se

dim

enta

ry

depo

sits

, co

lluv

ial

depo

sits

co

nsis

t of

la

g gr

avel

s of

va

rnis

hed

pebb

les

and

cobb

les.

Deb

ris

apro

ns t

ypic

ally

are

dis

sect

ed a

nd

part

ially

ero

ded,

lea

ving

res

ista

nt f

latir

ons

of r

elic

t co

lluvi

um o

n sl

opes

ero

ded

into

les

s re

sist

ant

subs

trat

e. O

n sl

opes

man

tled

with

mor

e th

an o

ne g

ener

atio

n of

col

luvi

um,

flat

iron

s of

suc

cess

ivel

y ol

der

depo

sits

cro

p ou

t pr

ogre

ssiv

ely

low

er o

n sl

opes

, pr

ovid

ing

a re

cord

of

eros

iona

l re

trea

t of

cap

ping

uni

t. W

ell-

deve

lope

d pa

vem

ents

on

collu

vial

dep

osits

are

ver

y da

rk a

nd s

moo

th, c

onsi

st o

f st

rong

ly v

arni

shed

peb

bles

and

cob

bles

, an

d ar

e un

derl

ain

by p

edog

enic

Av

hori

zon

of v

ery

pale

bro

wn

(10Y

R 7

/3),

loes

s-lik

e, v

esic

ular

silt

. Inc

lude

s:U

nit

2—V

arni

shed

deb

ris

apro

ns p

rese

rved

in

flat

iron

s on

slo

pes

belo

w c

ap

rock

Uni

t 1—

Var

nish

ed d

ebri

s ap

rons

pre

serv

ed i

n fl

atir

ons

on s

lope

s be

low

cap

ro

ck

VE

RY

OL

D S

UR

FIC

IAL

DE

PO

SIT

S—D

epos

its in

allu

vial

fan

s an

d on

pie

dmon

t sl

opes

. V

ery

old

depo

sits

ex

hibi

t st

rong

ly

diss

ecte

d ge

omor

phic

su

rfac

es

char

acte

rize

d by

tru

ncat

ed A

v/K

soi

l pr

ofile

s; c

arbo

nate

mor

phol

ogy

in K

hor

izon

is

cons

iste

nt w

ith p

edog

enes

is in

the

rang

e of

Sta

ge I

V-V

I; p

erva

sive

har

d to

ver

y ha

rd

chal

ky c

emen

tatio

n is

typi

cally

acc

ompa

nied

by

abun

dant

vei

ns o

f la

min

ar c

alcr

ete

Ver

y ol

d al

luvi

al d

epos

its

(ear

ly P

leis

toce

ne)—

Mod

erat

ely

to w

ell-

cem

ente

d sa

nd

and

boul

der

grav

el; u

nit e

xhib

its r

idge

-and

-rav

ine

(bal

lena

) m

orph

olog

y. R

idge

s ar

e ro

unde

d an

d lit

tere

d w

ith c

alcr

ete

frag

men

ts;

no r

emai

ning

pav

emen

t. A

s m

appe

d, m

ay in

clud

e qu

artz

ite-c

last

con

glom

erat

e un

it ( Q

Tcq

)

QU

AT

ER

NA

RY

AN

D (

OR

) TE

RT

IAR

Y S

UR

FIC

IAL

DE

PO

SIT

SC

ongl

omer

ate,

qu

artz

ite-

clas

t (Q

uate

rnar

y an

d (o

r)

Ter

tiar

y)—

Bou

lder

co

nglo

mer

ate

and

sand

ston

e sh

ed i

n co

arse

all

uvia

l ap

ron

from

qua

rtzi

te

outc

rops

on

Pint

o M

ount

ain

Sedi

men

tary

dep

osit

s, u

ndiv

ided

(Q

uate

rnar

y an

d (o

r) T

erti

ary)

—In

terp

rete

d fr

om a

eria

l ph

otog

raph

s. A

s m

appe

d, m

ay i

nclu

de p

arts

of

units

Qvo

a, T

s,

QT

cq, a

nd (

or)

Tert

iary

sap

rolit

e

CO

VE

R R

OC

KS

Sedi

men

tary

str

ata

of P

into

Bas

in (

Ple

isto

cene

and

(or

) P

lioc

ene)

—T

ilte

d se

dim

enta

ry s

trat

a in

Pin

to B

asin

sou

th o

f Pi

nto

Was

h. O

utcr

ops

of la

ke b

eds

in

cent

er o

f ba

sin

are

prob

ably

Plio

cene

; ou

tcro

ps o

f ar

kosi

c sa

ndst

one

just

nor

th

of H

exie

Mou

ntai

ns m

ay b

e Pl

ioce

ne o

r Pl

eist

ocen

e. I

nclu

des:

Con

glom

erat

e be

ds—

Bou

lder

con

glom

erat

e fo

rmin

g co

arse

allu

vial

bed

or

beds

de

rive

d fr

om P

rote

rozo

ic r

ocks

in H

exie

Mou

ntai

ns. I

n ea

st-c

entr

al P

into

Bas

in,

cong

lom

erat

e ov

erlie

s an

d m

ay i

nter

fing

er w

ith l

acus

trin

e de

posi

ts (

QT

pbl);

pr

oxim

al t

o H

exie

Mou

ntai

ns,

very

sim

ilar

boul

der

cong

lom

erat

e m

appe

d as

ol

d al

luvi

al d

epos

its,

mid

dle

unit

1 ( Q

oam

1) o

verl

ies

arko

sic

sand

ston

e be

ds

( QT

pbs)

; D

ebri

s fl

ow d

epos

its—

Mat

rix-

supp

orte

d se

dim

enta

ry b

recc

ia c

onta

inin

g co

bble

-si

zed

clas

ts d

eriv

ed f

rom

Jur

assi

c pl

uton

ic r

ocks

in

Pint

o M

ount

ains

; ov

erlie

s la

cust

rine

bed

s ( Q

Tpb

l)Sa

ndst

one

beds

—R

edde

ned

arko

sic

sand

ston

e. C

ross

-bed

ded,

coa

rse-

grai

ned

sand

ston

e co

ntai

ning

sca

ttere

d le

nses

of

pebb

le c

ongl

omer

ate

Lac

ustr

ine

beds

—C

lays

tone

and

mud

ston

e be

ds c

onta

inin

g in

terb

eds

of s

iltst

one

and

fine

- to

coa

rse-

grai

ned

sand

ston

e. S

ome

sand

ston

e be

ds a

re c

emen

ted

with

w

hite

cal

cite

; inc

lude

s at

leas

t one

thin

bed

of

fres

h-w

ater

lim

esto

neB

asal

t (l

ate

and

mid

dle

Mio

cene

)—B

asal

t fl

ows;

oliv

ine-

bear

ing,

mas

sive

, bl

ack.

M

icro

phen

ocry

sts

incl

ude

euhe

dral

la

ths

of

labr

ador

ite,

eu

hedr

al

oliv

ine

part

iall

y al

tere

d to

id

ding

site

, an

d cl

inop

yrox

ene.

O

ccur

s as

tw

o sm

all

expo

sure

s in

nor

thea

ster

n co

rner

of

quad

rang

le a

nd m

ore

exte

nsiv

ely

east

of

quad

rang

le

in

nort

hern

E

agle

an

d so

uthe

rn

Pin

to

Mou

ntai

ns.

Sou

th

of

quad

rang

le,

form

s pi

pes

and

(or)

nea

r-ve

nt f

low

s on

sm

all

inse

lber

gs r

isin

g ab

ove

pedi

men

t th

at f

orm

s so

uth

slop

e of

Pin

to B

asin

. Si

mila

r fl

ows

in E

agle

M

ount

ains

sou

thea

st o

f qu

adra

ngle

yie

ld w

hole

-roc

k co

nven

tiona

l K-A

r ag

es o

f 7.

8 an

d 10

.2 M

a (C

arte

r an

d ot

hers

, 198

7)Se

dim

enta

ry d

epos

its

(lat

e? a

nd m

iddl

e M

ioce

ne)—

Ark

osic

san

dsto

ne a

nd

silts

tone

; m

inor

con

glom

erat

e. A

s m

appe

d, m

ay i

nclu

de T

ertia

ry w

eath

erin

g re

golit

h. R

estr

icte

d to

sin

gle

expo

sure

in n

orth

east

ern

corn

er o

f qu

adra

ngle

CR

YST

AL

LIN

E B

ASE

ME

NT

RO

CK

SD

ike

rock

s,

undi

vide

d (T

erti

ary,

C

reta

ceou

s,

and

(or)

Ju

rass

ic)—

Dac

ite

porp

hyry

, m

icro

dior

ite,

and

quar

tz l

atite

or

rhyo

daci

te d

ikes

. N

ames

are

bas

ed

on p

heno

crys

t per

cent

ages

. Dac

ite d

ikes

are

gra

y ho

rnbl

ende

-fel

dspa

r po

rphy

ry

cont

aini

ng a

bund

ant

to s

pars

e ph

enoc

ryst

s of

zon

ed e

uhed

ral

plag

iocl

ase

(lab

rado

rite

to

an

desi

ne)

as

larg

e as

1

cm,

subo

rdin

ate

euhe

dral

br

own

horn

blen

de

and

brow

n bi

otit

e,

and

rare

em

baye

d qu

artz

se

t in

a

gray

m

icro

crys

tall

ine

grou

ndm

ass

of p

lagi

ocla

se,

alka

li f

elds

par,

quar

tz,

sphe

ne,

apat

ite,

and

zirc

on.

Dac

ite d

ikes

tre

nd n

orth

east

and

are

typ

ical

ly a

few

met

ers

thic

k, s

ever

al h

undr

ed m

eter

s lo

ng, a

nd d

ip s

teep

ly. T

hey

form

res

ista

nt r

ibs

and

exhi

bit

dark

bro

wn

pati

na o

f de

sert

var

nish

. S

imil

ar d

acit

e di

kes

intr

ude

Cre

tace

ous

gran

odio

rite

and

mon

zogr

anite

in

Eag

le M

ount

ains

sou

thea

st o

f qu

adra

ngle

. Mic

rodi

orite

dik

es a

re m

ediu

m-

to d

ark-

gree

nish

gra

y, f

ine-

to v

ery

fine

-gra

ined

, an

d co

mpo

sed

prim

arily

of

horn

blen

de a

nd p

lagi

ocla

se;

typi

cally

al

tere

d pr

opyl

itic

ally

to

epid

ote,

chl

orit

e, a

nd c

alci

te.

Qua

rtz

lati

te d

ikes

ty

pica

lly t

rend

nor

th a

nd a

re l

ight

to

med

ium

gra

y, s

ilice

ous,

aph

aniti

c ro

cks

cont

aini

ng m

icro

phen

ocry

sts

of q

uart

z, m

icro

clin

e, p

lagi

ocla

se,

and

biot

ite. A

qu

artz

lat

ite d

ike

in B

ig W

ash

in e

ast-

cent

ral

Eag

le M

ount

ains

yie

lds

a zi

rcon

U

-Pb

inte

rcep

t age

of

145

Ma

and

a sp

hene

U-P

b ag

e of

142

Ma

(Jam

es, 1

989)

Hyp

abys

sal i

ntru

sive

roc

ks (

Tert

iary

, Cre

tace

ous,

or

Jura

ssic

)—In

terp

rete

d fr

om

colo

r ae

rial

pho

togr

aphs

on

basi

s of

col

or a

nd s

heen

sim

ilar

to

thos

e of

hy

paby

ssal

dik

e ro

cks

( TJd

u). R

estr

icte

d to

sin

gle

loca

lity

nort

h of

Pin

to W

ash

near

wes

t edg

e of

qua

dran

gle

Gra

nite

of

Pin

to W

ash

(Lat

e or

Mid

dle

Jura

ssic

)—G

rani

te;

pea-

size

d (2

-5 m

m)

phen

ocry

sts

of q

uart

z in

fin

e- to

med

ium

-gra

ined

mat

rix

of q

uart

z an

d fe

ldsp

ar;

leuc

ocra

ticQ

uart

z m

onzo

nite

, m

onzo

gran

ite,

and

gra

nodi

orit

e of

San

Ber

nard

ino

Was

h (M

iddl

e Ju

rass

ic)—

Ran

ges

from

dio

rite

to

gran

ite;

pre

dom

inan

tly

quar

tz

mon

zoni

te,

mon

zogr

anit

e, a

nd g

rano

dior

ite.

Ext

ensi

vely

exp

osed

in

east

ern

Pint

o an

d so

uthe

ast

of q

uadr

angl

e in

nor

thea

ster

n E

agle

Mou

ntai

ns (

Inde

x M

ap).

Typ

ical

ly c

onta

ins

less

tha

n 25

per

cent

qua

rtz;

por

phyr

itic

rock

s ar

e ch

arac

teri

zed

by l

aven

der-

tinte

d ph

enoc

ryst

s of

alk

ali

feld

spar

. M

afic

min

eral

s co

nsis

t of

hor

nble

nde,

bio

tite,

and

loc

ally

clin

opyr

oxen

e; a

bund

ant

sphe

ne.

Roc

ks s

how

wid

espr

ead

prop

yliti

c al

tera

tion.

Inc

lude

s:

115˚

52'

30"

34˚

115˚

45'

00"

34˚

115˚

45'

00"

33˚

52' 3

0"

115˚

52'

30"

33˚

52' 3

0"

Geo

logy

map

ped

by R

.E.

Pow

ell,

1975

-85;

19

98-2

000;

st

ruct

ural

po

int

data

col

lect

ed b

y P

owel

l and

by

R

.A.

Hop

e,

1964

-69

(Hop

e,

1966

)

VE

RY

YO

UN

G S

UR

FIC

IAL

DE

PO

SIT

S—L

oose

to s

light

ly c

onso

lidat

ed a

lluvi

al

depo

sits

in

was

hes

inci

sed

both

int

o be

droc

k an

d in

to o

ther

Qua

tern

ary

units

and

gr

aded

to

base

-lev

el p

laya

dep

osits

in

Chu

ckw

alla

Val

ley

(Ind

ex M

ap).

Geo

mor

phic

su

rfac

es u

ndis

sect

ed t

o sl

ight

ly d

isse

cted

and

cha

ract

eriz

ed b

y ac

tive

or r

ecen

tly

activ

e se

dim

ent a

ccum

ulat

ion

Ver

y yo

ung

allu

vial

de

posi

ts,

undi

vide

d (l

ate

Hol

ocen

e)—

Unc

onso

lida

ted

med

ium

- to

coa

rse-

grai

ned

sand

and

san

dy g

rave

l, in

clud

ing

subo

rdin

ate

fine

sa

nd a

nd s

ilt;

bar

and

sw

ale

mor

phol

ogy;

unv

arni

shed

cla

sts.

Spa

rsel

y to

m

oder

atel

y ve

geta

ted;

pro

min

ent

ripa

rian

shr

ub l

ines

. C

hief

ly d

egra

datio

nal.

Incl

udes

:V

ery

youn

g al

luvi

al d

epos

its,

Uni

t 2—

Whi

te o

n co

lor

aeri

al p

hoto

grap

hs; n

o so

il pr

ofil

e de

velo

pmen

t. M

ostl

y sa

nd i

n w

ashe

s de

velo

ped

on s

lope

s fl

anki

ng

gran

ite i

nsel

berg

s. T

rans

port

ed a

nd d

epos

ited

in m

ost

rece

ntly

act

ive

chan

nels

; in

set i

nto

Qvy

a 1 a

nd o

lder

dep

osits

. Uni

t sur

face

s co

rrel

ativ

e w

ith Q

4b s

urfa

ces

of B

ull (

1991

)V

ery

youn

g al

luvi

al d

epos

its,

Uni

t 1—

Lig

ht g

ray

(2.5

YR

7/2

) to

pal

e ye

llow

; gr

ay

on

colo

r ae

rial

ph

otog

raph

s;

litt

le

or

no

soil

pr

ofil

e de

velo

pmen

t. T

rans

port

ed a

nd d

epos

ited

in c

hann

els

or p

arts

of

chan

nels

les

s re

cent

ly a

ctiv

e th

an t

hose

in

whi

ch u

nit

Qvy

a 2 d

epos

ited;

inc

ised

int

o yo

ung

allu

vial

and

old

er

depo

sits

. U

nit

surf

aces

cor

rela

tive

with

Q4a

and

(or

) Q

4b s

urfa

ces

of B

ull

(199

1)

VE

RY

YO

UN

G A

ND

(O

R) Y

OU

NG

SU

RF

ICIA

L D

EP

OSI

TS

Ver

y yo

ung

and

(or)

you

ng e

olia

n de

posi

ts (

Hol

ocen

e)—

Win

dblo

wn

sand

, un

cons

olid

ated

. W

here

it

occu

rs i

n di

scon

tinuo

us s

urfi

cial

ven

eers

, Q

vyye

is

repr

esen

ted

by a

red

-dot

ove

rlay

pat

tern

. A

s m

appe

d, m

ay i

nclu

de o

ld e

olia

n de

posi

tsV

ery

youn

g an

d (o

r) y

oung

pla

ya d

epos

its

(Hol

ocen

e)—

Mic

aceo

us s

ilt a

nd c

lay

cont

aini

ng m

inor

san

d an

d sc

atte

red

gran

ules

and

peb

bles

; ve

ry p

ale

brow

n to

pa

le

brow

n.

Lig

ht-c

olor

ed

surf

ace

on

aeri

al

phot

ogra

phs.

S

pars

ely

to

mod

erat

ely

vege

tate

d. O

ccur

s in

tw

o sm

all

area

s of

pon

ded

mud

ston

e, o

ne

alon

g Pi

nto

Was

h on

eas

t-ce

ntra

l ed

ge o

f qu

adra

ngle

and

one

aga

inst

low

hill

s of

upl

ifte

d st

rata

of

Pint

o B

asin

sou

th o

f Pi

nto

Was

h. O

lder

par

ts o

f th

is u

nit

over

lain

loca

lly b

y w

indb

low

n sa

nd a

nd d

ista

l fan

dep

osits

YO

UN

G S

UR

FIC

IAL

DE

PO

SIT

S—L

oose

to

mod

erat

ely

cons

olid

ated

all

uvia

l an

d eo

lian

depo

sits

on

pied

mon

t slo

pes.

Allu

vial

dep

osits

exh

ibit

slig

htly

to s

tron

gly

diss

ecte

d ge

omor

phic

sur

face

s ch

arac

teri

zed

by A

v/C

ox o

r A

v/B

w/C

ox s

oil

prof

iles

typi

cal

of H

oloc

ene

surf

aces

(M

cFad

den,

198

8; B

ull,

1991

). D

epos

its f

orm

a t

hin

man

tle s

prea

d ac

ross

land

scap

e in

heri

ted

from

Ple

isto

cene

You

ng a

lluvi

al d

epos

its,

und

ivid

ed (

Hol

ocen

e)—

Loo

se to

mod

erat

ely

cons

olid

ated

al

luvi

um d

epos

ited

in c

anyo

n bo

ttom

s an

d on

pie

dmon

t slo

pes.

Fan

s sp

read

out

as

agg

rada

tion

al a

pron

s ac

ross

inh

erit

ed P

leis

toce

ne l

ands

cape

, ba

ck-f

ille

d dr

aina

ge w

ashe

s fr

om w

hich

the

y em

anat

ed,

and

grew

pro

gres

sive

ly d

own-

pied

mon

t in

nes

ted

com

plex

es;

olde

st f

ans

are

prox

imal

to

rang

e-fr

ont

and

youn

gest

fan

s oc

cur

on l

ower

pie

dmon

t. Su

cces

sive

ly y

oung

er f

ans

are

inse

t in

to o

lder

fan

s at

the

ir a

pice

s an

d ei

ther

bur

y or

fea

ther

out

ont

o ol

der

fans

di

stal

ly.

Aba

ndon

ed s

urfa

ces

are

char

acte

rize

d by

ped

ogen

ic A

v ho

rizo

n of

lo

ess-

like,

ves

icul

ar l

ight

bro

wn

(10Y

R 6

/4)

calc

areo

us s

ilt.

Fan

surf

aces

are

no

t di

ssec

ted

by s

trea

ms

that

ori

gina

te o

n th

e su

rfac

es.

Pie

dmon

t al

luvi

al

depo

sits

co

mpr

ise

two

clas

ses

asso

ciat

ed

wit

h ge

omor

phic

ally

di

stin

ct

pied

mon

t se

tting

s: C

lass

1—

Dep

osits

for

min

g al

luvi

al a

pron

s ch

arac

teri

zed

by

prom

inen

tly c

one-

shap

ed,

mul

ti-lo

bed

fans

tha

t co

ales

ce i

nto

baja

das

dow

n-pi

edm

ont.

Typi

call

y oc

cur

alon

g ba

ses

of s

teep

, fa

ult-

cont

roll

ed m

ount

ain

esca

rpm

ents

dev

elop

ed i

n re

sist

ant

rock

s ha

ving

wea

ther

ing

and

denu

datio

n ch

arac

teri

stic

s th

at a

re r

elat

ivel

y in

sens

itive

to

clim

atic

cha

nge

(see

Bul

l, 19

91,

p. 1

61-1

67).

Cla

ss 2

—D

epos

its t

hat

accu

mul

ated

on

broa

d pi

edm

ont

slop

es

deve

lope

d on

les

s re

sist

ant

rock

s al

ong

deep

ly e

mba

yed

mou

ntai

n fr

onts

. W

eath

erin

g an

d de

nuda

tion

of t

hese

les

s re

sist

ant

rock

s ar

e re

lativ

ely

sens

itive

to

clim

atic

cha

nge.

Pie

dmon

ts a

re p

unct

uate

d w

ith i

nsel

berg

s, r

imm

ed w

ith

pedi

men

ts,

and

exhi

bit

broa

d, m

ulti-

face

ted

slop

es t

hat

drai

n vi

a sm

all

intr

a-pi

edm

ont

valle

ys b

etw

een

slop

e fa

cets

. Allu

vium

on

slop

e fa

cets

ori

gina

tes

as

fans

dis

trib

uted

fro

m f

eede

r dr

aina

ge-c

hann

els

and

as s

heet

was

h on

slo

pes

betw

een

drai

nage

cha

nnel

s. F

ans

in c

lass

2 p

iedm

ont

setti

ngs

are

char

acte

rize

d by

lo

w-c

onve

xity

tr

ansv

erse

pr

ofil

es,

and

by

surf

aces

ha

ving

lo

w-r

elie

f m

orph

olog

y. F

ans

and

shee

twas

h on

slo

pes

betw

een

fans

com

mon

ly m

erge

im

perc

epti

bly.

Dow

n-pi

edm

ont,

dist

ribu

tary

slo

pe d

rain

age

re-c

olle

cts

into

in

tra-

pied

mon

t tr

ibut

ary

valle

ys t

hat,

in t

urn,

deb

ouch

ont

o fa

ns f

arth

er d

own-

pied

mon

t. D

epos

its

are

form

ed

by

chan

neli

zed

flow

an

d by

un

conf

ined

ov

erla

nd f

low

in

dist

ribu

ted

netw

ork

of b

ranc

hing

and

coa

lesc

ing

was

hes,

fan

s,

and

thin

slo

pe-b

lank

etin

g sh

eets

. You

ng a

lluvi

al d

epos

its a

re d

ivid

ed i

nto

old,

m

iddl

e, a

nd y

oung

sub

units

rou

ghly

equ

ival

ent

to Q

3a,b

,c u

nits

of

Bul

l (1

991)

. T

hese

uni

ts a

re f

urth

er s

ubdi

vide

d as

nee

ded.

Con

sist

s of

: Y

oung

al

luvi

al

depo

sits

, yo

ung

unit

, un

divi

ded

(lat

e an

d (o

r)

mid

dle

Hol

ocen

e)—

On

clas

s 1

pied

mon

ts, u

nit

show

s pa

le b

row

nish

gra

y to

pal

e gr

ay

on c

olor

aer

ial p

hoto

grap

hs; s

urfa

ces

exhi

bit b

raid

ed b

ar a

nd s

wal

e m

orph

olog

y ge

nera

ted

by a

nast

omos

ing

chan

nels

. U

ncon

solid

ated

san

d an

d gr

avel

, po

orly

to

mod

erat

ely

sort

ed;

mor

e sa

nd a

nd l

ess

grav

el t

han

olde

r Q

ya u

nits

. L

ittle

or

no d

eser

t va

rnis

h. S

urfa

ces

corr

elat

ive

with

Q3c

and

(or

) Q

4b s

urfa

ces

of B

ull

(199

1).

On

clas

s 2

pied

mon

ts,

unco

nsol

idat

ed s

and

and

pebb

ly s

and,

poo

rly

to

mod

erat

ely

sort

ed.

Prox

imal

ly,

depo

sits

are

ins

et i

nto

olde

r Q

ya u

nits

; di

stal

ly,

they

fea

ther

out

ont

o su

rfac

es o

f Q

yam

uni

ts.

Surf

aces

cor

rela

ted

with

Q3c

su

rfac

es o

f B

ull (

1991

). C

onsi

sts

of:

You

ng a

lluvi

al d

epos

its,

you

ng u

nit,

gra

velly

fac

ies—

Gra

vell

y al

luvi

um

form

ing

feed

er-c

hann

el d

epos

its i

n ca

nyon

-bot

tom

s an

d fa

ns p

roxi

mal

to

stee

p ra

nge

fron

ts.

In P

into

Mou

ntai

n qu

adra

ngle

, fa

n de

posi

ts o

ccur

in

clas

s 1

pied

mon

t set

ting

Y

oung

allu

vial

dep

osit

s, y

oung

uni

t, s

andy

fac

ies—

Sand

y al

luvi

um f

orm

ing

valle

y-bo

ttom

dep

osits

, fan

s an

d fa

n-sk

irts

dis

tal t

o st

eep

rang

e fr

onts

on

clas

s 1

pied

mon

ts,

and

allu

vial

-apr

on d

epos

its o

n cl

ass

2 pi

edm

onts

dee

ply

emba

yed

into

mou

ntai

n fr

onts

Y

oung

allu

vial

san

d-sk

irt

depo

sits

(H

oloc

ene)

—D

ista

l sa

nd d

epos

its a

t to

es o

f al

luvi

al f

ans;

at l

east

in p

art r

ewor

ked

as w

indb

low

n sa

ndY

oung

allu

vial

dep

osit

s, m

iddl

e un

it,

undi

vide

d (m

iddl

e H

oloc

ene)

—O

n cl

ass

1 pi

edm

onts

, Q

yam

u fo

rmin

g gr

avel

ly p

roxi

mal

par

ts o

f fa

ns i

s gr

ay o

n co

lor

aeri

al p

hoto

grap

hs;

grav

elly

and

san

dy m

edia

l pa

rts

are

mot

tled

gray

and

pal

e br

owni

sh g

ray;

san

dy d

ista

l pa

rts

are

pale

to

med

ium

bro

wni

sh g

ray.

Sur

face

s on

gra

velly

par

ts o

f fa

ns e

xhib

it pl

umos

e ba

r an

d sw

ale

mor

phol

ogy;

sur

face

s on

san

dy p

arts

of

fans

exh

ibit

brai

ded

bar

and

swal

e m

orph

olog

y ge

nera

ted

by

anas

tom

osin

g ch

anne

ls. U

ncon

solid

ated

to c

onso

lidat

ed s

and

and

grav

el, p

oorl

y to

mod

erat

ely

sort

ed.

Mod

erat

e va

rnis

h on

gra

velly

pro

xim

al p

arts

of

fans

; sw

ales

exh

ibit

pebb

ly p

avem

ents

und

erla

in b

y A

v ho

rizo

n. S

urfa

ces

corr

elat

ive

with

Q3b

sur

face

s of

Bul

l (1

991)

. O

n cl

ass

2 pi

edm

onts

, un

cons

olid

ated

san

d an

d gr

avel

, po

orly

to

mod

erat

ely

sort

ed.

Surf

aces

ten

tativ

ely

corr

elat

ed w

ith

Q3b

sur

face

s of

Bul

l (19

91).

Inc

lude

s:Y

oung

allu

vial

dep

osit

s, m

iddl

e un

it,

grav

elly

fac

ies,

und

ivid

ed—

Gra

velly

al

luvi

um f

orm

ing

feed

er-c

hann

el d

epos

its in

can

yon-

botto

ms

and

fans

pro

xim

al

to s

teep

ran

ge f

ront

s. I

n Pi

nto

Mou

ntai

n qu

adra

ngle

, fan

dep

osits

occ

ur in

cla

ss

1 pi

edm

ont s

ettin

g. L

ocal

ly, d

ivid

ed in

to:

You

ng a

lluvi

al d

epos

its,

mid

dle

unit

, gra

velly

fac

ies

2—Y

oung

er g

rave

lly

allu

vial

dep

osits

of

mid

dle

unit;

for

m f

ans

that

deb

ouch

fro

m c

hann

els

inci

sed

into

old

er g

rave

lly d

epos

its o

f m

iddl

e un

it Y

oung

allu

vial

dep

osit

s, m

iddl

e un

it,

grav

elly

fac

ies

1—O

lder

gra

velly

al

luvi

al d

epos

its o

f m

iddl

e un

itY

oung

allu

vial

dep

osit

s, m

iddl

e un

it, s

andy

fac

ies—

Sand

y al

luvi

um f

orm

ing

valle

y-bo

ttom

dep

osits

, fan

s an

d fa

n-sk

irts

dis

tal t

o st

eep

rang

e fr

onts

on

clas

s 1

pied

mon

ts,

and

allu

vial

-apr

on d

epos

its o

n cl

ass

2 pi

edm

onts

dee

ply

emba

yed

into

mou

ntai

n fr

onts

Por

phyr

itic

uni

t—M

ediu

m-

to c

oars

e-gr

aine

d po

rphy

ritic

plu

toni

c ro

cks;

var

y in

co

mpo

siti

on

from

qu

artz

m

onzo

nite

to

m

onzo

gran

ite

and

gran

odio

rite

. U

nfol

iate

d to

fol

iate

d. H

ornb

lend

e-bi

otite

to

biot

ite-h

ornb

lend

e; p

heno

crys

ts

are

lave

ndar

-tin

ted

to p

inki

sh-g

ray

alka

li fe

ldsp

ar;

prop

yliti

cally

alte

red.

Yie

lds

biot

ite c

onve

ntio

nal

K-A

r ag

e of

167

Ma

(Bis

hop,

196

3) i

n Pi

nto

Mou

ntai

ns

nort

h of

qua

dran

gle

and

zirc

on U

-Pb

ages

of

abou

t 16

5 M

a (S

ilver

, 19

78,

oral

co

mm

unic

atio

n; W

oode

n an

d ot

hers

, 19

94)

in P

into

Mou

ntai

ns n

orth

of

quad

rang

le a

nd in

Eag

le M

ount

ains

sou

thea

st o

f qu

adra

ngle

Maf

ic a

nd i

nter

med

iate

int

rusi

ve s

uite

, un

divi

ded

(Jur

assi

c)—

Inte

rmin

gled

m

afic

and

maf

ic i

nter

med

iate

roc

ks o

f va

ried

com

posi

tion

and

text

ure.

Col

or

inde

x ra

nges

fr

om

50

to

>95

. In

clud

es

coar

se-

to

very

co

arse

-gra

ined

ho

rnbl

endi

te

and

horn

blen

de

gabb

ro,

med

ium

- to

co

arse

-gra

ined

bi

otit

e-ho

rnbl

ende

dio

rite

, fin

e-gr

aine

d, d

ark-

colo

red

dior

ite to

qua

rtz

dior

ite, m

ediu

m-

grai

ned

dior

ite

and

quar

tz d

iori

te,

and

coar

se-

to e

xtre

mel

y co

arse

-gra

ined

ga

bbro

-dio

riti

c pe

gmat

ite.

In

trud

ed

by

porp

hyri

tic

quar

tz

mon

zoni

te,

mon

zogr

anite

, and

gra

nodi

orite

of

San

Ber

nard

ino

Was

h ( J

sbp)

. Inc

lude

s:D

ark

unit

—E

spec

ially

dar

k-w

eath

erin

g m

afic

roc

k as

int

erpr

eted

on

colo

r ae

rial

ph

otog

raph

s. R

estr

icte

d to

sou

ther

n m

argi

n of

Pin

to M

ount

ains

in q

uadr

angl

eG

neis

s as

sem

blag

e of

Hex

ie M

ount

ains

(E

arly

Pro

tero

zoic

)—O

rtho

gnei

ss a

nd

para

gnei

ss.

Str

atig

raph

ic,

and

intr

usiv

e re

lati

ons

betw

een

cons

titu

ent

unit

s ty

pica

lly o

verp

rint

ed b

y m

etam

orph

ic a

nd d

efor

mat

iona

l eve

nts

(Pow

ell,

1993

).

Wid

espr

ead

in

the

Hex

ie,

wes

tern

P

into

, so

uthe

aste

rn

Eag

le,

Oro

copi

a,

Chu

ckw

alla

and

Litt

le C

huck

wal

la M

ount

ains

(In

dex

Map

). C

onsi

sts

of:

Pin

to G

neis

s of

Mill

er,

1938

(E

arly

Pro

tero

zoic

)—In

term

ingl

ed o

rtho

- an

d pa

ragn

eiss

. W

ides

prea

d in

th

e w

este

rn

Pin

to,

Hex

ie,

Cot

tonw

ood,

an

d C

huck

wal

la M

ount

ains

; al

so c

rops

out

in

sout

hwes

tern

Eag

le a

nd e

aste

rnm

ost

Oro

copi

a M

ount

ains

. R

estr

icte

d to

ro

cks

incl

uded

in

M

ille

r's

orig

inal

de

scri

ptio

n of

uni

t; do

es n

ot i

ncor

pora

te e

xpan

ded

usag

e of

Rog

ers

(196

1).

Incl

udes

:P

into

Gne

iss,

leuc

ocra

tic

gran

itic

ort

hogn

eiss

—Fo

liate

d, l

inea

ted

leuc

ocra

tic

biot

ite g

rani

te t

o gr

aniti

c gn

eiss

, m

ediu

m-

to v

ery

coar

se-g

rain

ed.

Con

sist

s of

al

kali

feld

spar

, pl

agio

clas

e, q

uart

z, a

nd b

iotit

e; g

arne

t is

com

mon

ly p

rese

nt a

s is

olat

ed ti

ny c

ryst

als

or a

s la

rge,

rec

ryst

alliz

ed c

lots

of

tiny

garn

ets

Pin

to G

neis

s, d

ark

unit

, un

divi

ded—

From

you

nges

t to

old

est,

incl

udes

: (1

) B

iotit

e-qu

artz

-fel

dspa

r gn

eiss

; pr

omin

ently

lay

ered

, ha

ving

alte

rnat

ing

light

-co

lore

d la

min

ae r

ich

in a

lkal

i fe

ldsp

ar a

nd d

ark-

colo

red

lam

inae

ric

h in

bio

tite

and

olig

ocla

se;

cont

ains

abu

ndan

t qu

artz

(30

-50%

); g

arne

t is

com

mon

; (2

) am

phib

olite

; an

d (3

) m

etas

edim

enta

ry a

nd (

or)

met

amor

phos

ed h

ydro

ther

mal

ly

alte

red

rock

s. I

nclu

des:

Met

ased

imen

tary

and

(or

) m

etam

orph

osed

hyd

roth

erm

ally

alt

ered

ro

cks

of P

inkh

am C

anyo

n, u

ndiv

ided

—R

egio

nally

, m

etas

edim

enta

ry r

ocks

co

mpr

ise

(a)

schi

stos

e ga

rnet

-sil

lim

anit

e/an

dalu

site

-mus

covi

te-b

ioti

te-q

uart

z-fe

ldsp

ar p

elit

ic g

neis

s, (

b) c

ompo

siti

onal

ly l

amin

ated

, si

lice

ous

gran

ofel

s

cons

isti

ng p

redo

min

antl

y of

qua

rtz

and

cord

ieri

te a

nd c

onta

inin

g va

ryin

g am

ount

s of

sill

iman

ite a

nd (

or)

anda

lusi

te,

garn

et,

stau

rolit

e, p

lagi

ocla

se,

and

alka

li fe

ldsp

ar,

bio

tite,

and

mus

covi

te,

(c)

blui

sh g

ray

silic

eous

gra

nofe

ls,

(d)

scat

tere

d th

in la

yers

of

ferr

omag

nesi

an s

chis

t and

gra

nofe

ls. I

nclu

des:

Silic

eous

gra

nofe

ls o

f W

ilson

Can

yon—

Blu

ish

gray

sili

ceou

s gr

anof

els

cons

isti

ng

pred

omin

antl

y of

co

arse

-gra

ined

qu

artz

an

d ve

ry

fine

-gra

ined

se

rici

te th

at h

as r

epla

ced

plag

iocl

ase

and

cord

ieri

te p

seud

omor

phic

ally

Eag

le M

ount

ains

ass

embl

age

(Pro

tero

zoic

)—R

egio

nal

grou

ping

of

met

amor

phic

ro

ck u

nits

com

pris

ing

gran

itic

bas

emen

t te

rran

e de

posi

tion

ally

ove

rlai

n by

m

etas

edim

enta

ry

supr

acru

stal

se

ctio

n.

Eag

le

Mou

ntai

ns

asse

mbl

age

is

wid

espr

ead

in E

agle

, Pin

to, a

nd C

huck

wal

la M

ount

ains

. Con

sist

s of

:M

etas

edim

enta

ry

rock

s (M

iddl

e or

E

arly

P

rote

rozo

ic)—

Met

amor

phos

ed

plat

form

sec

tion

of

quar

tzit

e, p

elit

ic s

chis

t an

d po

rphy

robl

asti

c gr

anof

els,

fe

rrif

erou

s fe

ldsp

athi

c sc

hist

, dol

omite

, and

min

or li

mes

tone

. Not

all

rock

type

s cr

op o

ut i

n Pi

nto

Mou

ntai

n qu

adra

ngle

. The

rmal

ly m

etam

orph

osed

thr

ough

out

regi

on.

Def

orm

ed i

n th

e C

huck

wal

la,

Eag

le,

and

sout

hern

Pin

to M

ount

ains

; un

defo

rmed

in c

entr

al P

into

Mou

ntai

ns. I

nclu

des:

Dol

omit

e of

Iro

n C

hief

min

e (M

iddl

e or

Ear

ly P

rote

rozo

ic)—

Ver

y co

arse

-gr

aine

d do

lom

ite m

arbl

e ha

ving

int

erlo

ckin

g re

crys

talli

zed

grai

ns a

s la

rge

as 1

cm

. W

hite

to

ligh

t gr

ay,

gray

ish

oran

ge (

10Y

R 7

/4)

to p

ale

yell

owis

h or

or

angi

sh b

row

n w

eath

erin

g. T

hin

to t

hick

-lay

ered

int

erva

ls r

ich

in d

ark-

brow

n w

eath

erin

g si

liceo

us n

odul

es,

pods

, an

d le

nses

; sp

orad

ic l

ayer

s of

ver

y co

arse

-gr

aine

d w

hite

ca

lcit

e m

arbl

e (<

3 m

th

ick)

, qu

artz

ite,

an

d da

rk-b

row

n-w

eath

erin

g he

mat

ite-

dolo

mit

e (i

ron

ore)

. C

onta

ins

scat

tere

d ca

lc-s

ilic

ate

min

eral

s, in

clud

ing

garn

et, d

iops

ide,

and

phl

ogop

iteQ

uart

zite

of

Pin

to M

ount

ain

(Mid

dle

or E

arly

Pro

tero

zoic

)—C

onsi

sts

of

thre

e in

terf

inge

ring

lith

ofac

ies:

(1)

gra

y to

blu

ish

gray

qua

rtzi

te, c

oars

e- to

ver

y co

arse

-gra

ined

, vitr

eous

, thi

n be

dded

to m

assi

ve, c

onta

inin

g gr

anul

e an

d pe

bble

co

nglo

mer

ate

beds

; (2)

whi

te q

uart

zite

, coa

rse-

to v

ery

coar

se-g

rain

ed, v

itreo

us,

mas

sive

; an

d (3

) pe

litic

roc

ks. I

nclu

des

two

sequ

ence

s of

uni

ts, o

ne d

esig

nate

d by

num

ber

and

one

by c

olor

and

com

posi

tion:

Uni

t 9—

Whi

te t

o lig

ht g

ray

quar

tzite

; ch

iefl

y in

terp

rete

d fr

om c

olor

aer

ial

phot

ogra

phs

Uni

t 8—

Dar

k gr

ay,

coar

se-g

rain

ed,

vitr

eous

qua

rtzi

te c

onta

inin

g gr

anul

e to

pe

bble

con

glom

erat

e be

ds; c

ross

-bed

ded;

upr

ight

Uni

t 7—

Pel

itic

roc

ks;

com

pose

d of

and

alus

ite,

whi

te m

ica,

and

qua

rtz.

Po

rphy

robl

astic

to

gran

obla

stic

; no

t fo

liate

d in

Pin

to M

ount

ains

; sc

hist

ose

in

Eag

le M

ount

ains

sou

thea

st o

f qu

adra

ngle

. W

ell

deve

lope

d pa

tina

of

dese

rt

varn

ish

mak

es u

nit s

how

as

dark

on

colo

r ae

rial

pho

togr

aphs

Uni

t 6—

Ver

y co

arse

-gra

ined

, vitr

eous

, whi

te to

ligh

t-gr

ay q

uart

zite

(98

-99%

qu

artz

) w

ith i

nter

lock

ing

grai

ns a

s la

rge

as 1

cm

. A

s m

appe

d, m

ay i

nclu

de

dom

ains

of

rem

obili

zed

quar

tz.

Uni

t 5—

Pel

itic

roc

ks;

com

pose

d of

and

alus

ite,

whi

te m

ica,

and

qua

rtz.

Po

rphy

robl

astic

to

gran

obla

stic

; no

t fo

liate

d in

Pin

to M

ount

ains

; sc

hist

ose

in

Eag

le M

ount

ains

sou

thea

st o

f qu

adra

ngle

. W

ell

deve

lope

d pa

tina

of

dese

rt

varn

ish

mak

es u

nit s

how

as

dark

on

colo

r ae

rial

pho

togr

aphs

Uni

t 4—

Dar

k gr

ay, c

oars

e-gr

aine

d, v

itreo

us q

uart

zite

with

gra

nule

to p

ebbl

e co

nglo

mer

ate

beds

; cro

ss-b

edde

d; u

prig

htU

nit

3—Pe

litic

roc

ks;

chie

fly

quar

tz-m

usco

vite

-sill

iman

ite/a

ndal

usite

roc

k.

Porp

hyro

blas

tic t

o gr

anob

last

ic;

not

folia

ted

in P

into

Mou

ntai

ns;

schi

stos

e in

E

agle

Mou

ntai

ns s

outh

east

of

quad

rang

leU

nit

2—V

ery

coar

se-g

rain

ed, v

itreo

us, w

hite

to li

ght-

gray

qua

rtzi

te (

98-9

9%

quar

tz)

wit

h in

terl

ocki

ng

grai

ns

as

larg

e as

1

cm;

grai

ns

are

stro

ngly

re

crys

tall

ized

and

hav

e su

ture

d bo

unda

ries

; no

evi

denc

e of

rel

ict

roun

ded

sedi

men

tary

gra

ins;

mas

sive

; be

ddin

g ob

scur

e or

obl

itera

ted;

thi

n se

ams

rich

in

redd

ish

blac

k he

mat

ite a

nd a

lum

inos

ilica

te m

iner

als.

As

map

ped,

may

inc

lude

do

mai

ns o

f re

mob

ilize

d qu

artz

Uni

t 1—

Mot

tled

light

- to

dar

k-gr

ay t

o bl

uish

-gra

y qu

artz

ite (

>95

% q

uart

z);

med

ium

bed

ded

to m

assi

ve;

cont

ains

and

alus

ite a

nd s

illim

anite

. C

ongl

omer

ate

occu

rs i

n la

yers

and

len

ses

as t

hick

as

3 m

nea

r un

conf

orm

ity a

t ba

se o

f qu

artz

ite u

nit.

Cla

sts

cons

ist

of p

ebbl

es a

nd c

obbl

es o

f (1

) ve

ry c

oars

e-gr

aine

d w

hite

qua

rtzi

te o

r qu

artz

(85

-95%

), (

2) t

abul

ar c

last

s of

fin

e-gr

aine

d bl

ack

spec

ular

hem

atit

e-ri

ch q

uart

zite

(5-

15%

), a

nd (

3) r

are

fine

-gra

ined

jas

per.

Mat

rix

is m

ottle

d lig

ht t

o da

rk g

ray

quar

tzite

. D

efor

med

cla

sts

have

asp

ect

ratio

s as

gre

at a

s 10

:2:1

. H

emat

ite i

mpa

rts

char

acte

rist

ic r

usty

bro

wn

stai

n.

Dep

osite

d no

ncon

form

ably

on

rego

lith

deve

lope

d on

gra

nite

of

Josh

ua T

ree

Gra

y un

it—

Gra

y qu

artz

ite.

On

east

fla

nk o

f P

into

Mou

ntai

n, c

hief

ly

inte

rpre

ted

from

col

or a

eria

l pho

togr

aphs

. Con

sist

s of

: L

ight

gra

y un

it—

Lig

ht-g

ray

to

gray

qu

artz

ite

(>95

%

quar

tz).

As

map

ped,

may

incl

ude

dom

ains

of

rem

obili

zed

quar

tzD

ark

gray

uni

t—D

ark-

gray

to b

luis

h-gr

ay q

uart

zite

(>

95%

qua

rtz)

Whi

te u

nit—

Ver

y co

arse

-gra

ined

, vi

treo

us,

whi

te t

o li

ght-

gray

qua

rtzi

te

(98-

99%

qua

rtz)

hav

ing

inte

rloc

king

gra

ins

as la

rge

as 1

cm

; gra

ins

are

stro

ngly

re

crys

tall

ized

and

hav

e su

ture

d bo

unda

ries

; no

evi

denc

e of

rel

ict

roun

ded

sedi

men

tary

gra

ins;

mas

sive

; be

ddin

g ob

scur

e or

obl

itera

ted.

As

map

ped,

may

in

clud

e do

mai

ns o

f re

mob

iliz

ed q

uart

z. O

n ea

st f

lank

of

Pin

to M

ount

ain,

ch

iefl

y in

terp

rete

d fr

om c

olor

aer

ial p

hoto

grap

hsP

elit

ic u

nit—

Dar

k m

etam

orph

osed

pel

itic

rock

s, c

onta

inin

g ve

ry a

bund

ant

alum

inos

ilica

te m

iner

als;

chi

efly

com

pose

d of

qua

rtz,

m

usco

vite

, si

llim

anite

an

d (o

r) a

ndal

usite

; bi

otite

-bea

ring

in

plac

es.

Porp

hyro

blas

tic t

o gr

anob

last

ic;

schi

stos

e to

unf

olia

ted

in P

into

Mou

ntai

ns.

Uni

t al

so c

onta

ins

dark

-col

ored

qu

artz

ite;

as m

appe

d, m

ay i

nclu

de b

odie

s of

Jur

assi

c m

afic

and

int

erm

edia

te

intr

usiv

e su

ite (

Jmiu

). O

n ea

st f

lank

of

Pint

o M

ount

ain,

chi

efly

inte

rpre

ted

from

co

lor

aeri

al p

hoto

grap

hs.

Wel

l de

velo

ped

patin

a of

des

ert

varn

ish

mak

es u

nit

show

as

dark

on

colo

r ae

rial

pho

togr

aphs

Met

amor

phos

ed r

egol

ith

(Mid

dle

or E

arly

Pro

tero

zoic

)—A

lum

inou

s ho

rizo

n at

top

of

gran

ite g

neis

s be

neat

h ov

erly

ing

quar

tzite

; 3

to 5

m t

hick

. Con

sist

s of

qu

artz

(50

-55%

), m

usco

vite

, an

d as

muc

h as

40

perc

ent

anda

lusi

te a

nd (

or)

sill

iman

ite.

In

terp

rete

d as

m

etam

orph

osed

w

eath

erin

g re

goli

th.

Fel

dspa

r ph

enoc

ryst

s in

gra

nite

ben

eath

reg

olith

are

inc

reas

ingl

y al

tere

d up

war

d to

war

d co

ntac

t (r

epre

sent

ed

by

incr

easi

ngly

ab

unda

nt

mus

covi

te

at

the

pres

ent

met

amor

phic

gra

de)

and

base

of

rego

lith

is m

arke

d by

abr

upt

disa

ppea

ranc

e of

fe

ldsp

ar.

Qua

rtz

grai

ns

have

ab

out

sam

e si

ze

rang

e an

d di

stri

buti

on

as

phen

ocry

sts

in

unde

rlyi

ng

gran

ite

gnei

ss.

Met

amor

phos

ed

rego

lith

is

po

rphy

robl

astic

gra

nofe

ls h

ere

in P

into

Mou

ntai

ns, w

here

it

is c

aps

porp

hyri

tic

gran

ite a

nd i

s ov

erla

in b

y un

defo

rmed

con

glom

erat

e. S

chis

tose

to

sout

heas

t in

C

onej

o W

ell

quad

rang

le,

whe

re

it

over

lies

gr

anit

e gn

eiss

an

d un

derl

ies

stre

tche

d-pe

bble

con

glom

erat

eG

rani

te g

neis

s of

Jos

hua

Tre

e (E

arly

Pro

tero

zoic

)—B

iotit

e-pl

agio

clas

e-qu

artz

-al

kali

feld

spar

fla

ser

auge

n gn

eiss

. L

ight

gra

y to

whi

te,

leuc

ocra

tic;

light

to

mod

erat

e ru

sty

brow

n pa

tina

on

wea

ther

ed s

urfa

ces.

Aug

en a

re t

ypic

ally

el

onga

te,

spin

dle-

shap

ed a

ggre

gate

s of

alk

ali

feld

spar

, pl

agio

clas

e, a

nd q

uart

z;

som

e au

gen

have

cor

es o

f m

icro

clin

e m

egac

ryst

s w

ith "

pres

sure

sha

dow

" ta

ils

of r

ecry

stal

lized

fin

er-g

rain

ed q

uart

z an

d fe

ldsp

ar.

Gne

issi

c fo

liatio

n ex

hibi

ted

as q

uart

zo-f

elds

path

ic l

ayer

s 1

to 2

cm

thi

ck s

epar

ated

by

wis

py,

disc

ontin

ous

stri

nger

s of

bi

otit

e.

Foli

a ty

pica

lly

are

fold

ed.

Uni

t yi

elds

U

-Pb

zirc

on

min

imum

age

of

1650

Ma

(L.T

. S

ilve

r, 1

978-

1980

, or

al c

omm

unic

atio

n).

Met

amor

phos

ed a

nd p

enet

rativ

ely

defo

rmed

aft

er d

evel

opm

ent

of w

eath

erin

g re

golit

h an

d de

posi

tion

of o

verl

ying

qua

rtzi

te o

f Pi

nto

Mou

ntai

nP

orph

yrit

ic g

rani

te o

f Jo

shua

Tre

e (E

arly

Pro

tero

zoic

)—Po

rphy

ritic

gra

nite

. L

ight

gra

y to

whi

te,

leuc

ocra

tic;

lig

ht t

o m

oder

ate

rust

y br

own

pati

na o

n w

eath

ered

sur

face

s. P

heno

crys

ts o

f w

hite

to

gray

alk

ali

feld

spar

and

gre

enis

h-w

hite

pla

gioc

lase

, an

d sp

hero

idal

qua

rtz

(<1

cm).

Les

s th

an 1

0 pe

rcen

t bi

otite

, ty

pica

lly i

n re

crys

talli

zed

clot

s. U

nit

yiel

ds U

-Pb

zirc

on m

inim

um a

ge o

f 16

50

Ma

(L.T

. Silv

er, 1

978-

1980

, ora

l com

mun

icat

ion)

1 N0T

E:

Thi

s ge

olog

ic m

ap i

s on

e re

pres

enta

tion

of

rock

uni

ts c

onta

ined

in

the

digi

tal

data

base

. T

he

data

base

al

so

desc

ribe

s a

hier

arch

ical

ar

ray

of

stra

tigr

aphi

c pa

rent

s of

the

map

ped

unit

s. T

he p

aren

t un

its

aggr

egat

e th

e ro

ck

unit

s sh

own

on t

his

map

and

can

be

used

to

gene

rate

and

dis

play

mor

e ge

nera

lize

d ge

olog

ic m

aps.

Som

e of

the

par

ent

unit

s ar

e de

scri

bed

here

in

this

D

escr

ipti

on o

f M

ap U

nits

; al

l ar

e de

scri

bed

in t

he D

escr

ipti

on o

f D

atab

ase

Uni

ts in

the

sum

mar

y pa

mph

let t

hat a

ccom

pani

es th

is O

pen-

Fil

e R

epor

t.

RE

FE

RE

NC

ES

CIT

ED

Bis

hop,

C. C

., co

mpi

ler,

1963

, Geo

logi

c m

ap o

f C

alif

orni

a; N

eedl

es s

heet

: C

alif

orni

a D

ivis

ion

of M

ines

and

Geo

logy

, sca

le 1

:250

,000

.B

ull,

W.B

., 19

91,

Geo

mor

phic

res

pons

es t

o cl

imat

ic c

hang

e: N

ew Y

ork,

Oxf

ord

Uni

vers

ity P

ress

, 326

p.

Car

ter,

J.N

., L

uyen

dyk,

B.P

., an

d Te

rres

, R

.R.,

1987

, N

eoge

ne c

lock

wis

e te

cton

ic

rota

tion

of

th

e ea

ster

n T

rans

vers

e R

ange

s,

Cal

ifor

nia,

su

gges

ted

by

pale

omag

netic

vec

tors

: G

eolo

gica

l So

ciet

y of

Am

eric

a B

ulle

tin,

v. 9

8, p

. 19

9-20

6.H

ope,

R.A

., 19

66,

Geo

logy

and

str

uctu

ral

setti

ng o

f th

e ea

ster

n T

rans

vers

e R

ange

s,

sout

hern

Cal

ifor

nia

[Ph.

D.

thes

is]:

Los

Ang

eles

, U

nive

rsity

of

Cal

ifor

nia,

158

p.

Jam

es,

E.W

., 19

89,

Sout

hern

ext

ensi

on o

f th

e In

depe

nden

ce d

ike

swar

m o

f ea

ster

n C

alif

orni

a: G

eolo

gy, v

. 17,

no.

7, p

. 587

-590

.M

cFad

den,

L.D

., 19

88, C

limat

ic in

flue

nces

on

rate

s an

d pr

oces

ses

of s

oil d

evel

opm

ent

in Q

uate

rnar

y de

posi

ts o

f so

uthe

rn C

alif

orni

a, in

Rei

nhar

dt, J

. and

Sig

leo,

W.R

., ed

s.,

Pal

eoso

ls

and

wea

ther

ing

thro

ugh

geol

ogic

ti

me:

P

rinc

iple

s an

d ap

plic

atio

ns: G

eolo

gica

l Soc

iety

of A

mer

ica

Spec

ial P

aper

216

, p. 1

53-1

77.

Mil

ler,

W.J

., 19

38,

Pre

-Cam

bria

n an

d as

soci

ated

roc

ks n

ear

Twen

ty-n

ine

Palm

s,

Cal

ifor

nia:

Geo

logi

cal S

ocie

ty o

f Am

eric

a B

ulle

tin, v

. 49,

p. 4

17-4

46.

Mun

sell

Col

or,

1975

, M

unse

ll so

il co

lor

char

ts,

1975

edi

tion:

Bal

timor

e, M

aryl

and,

M

acbe

th D

ivis

ion

of K

ollm

orge

n C

orpo

ratio

n.P

owel

l, R

.E.,

1993

, B

alan

ced

pali

nspa

stic

re

cons

truc

tion

of

pr

e-la

te

Cen

ozoi

c pa

leog

eolo

gy,

sout

hern

Cal

ifor

nia:

Geo

logi

c an

d ki

nem

atic

con

stra

ints

on

evol

utio

n of

the

San

And

reas

fau

lt sy

stem

, in

Pow

ell,

R.E

., W

eldo

n, R

.J.,

II, a

nd

Mat

ti, J

.C.,

eds.

, T

he S

an A

ndre

as f

ault

syst

em:

Dis

plac

emen

t, pa

linsp

astic

re

cons

truc

tion,

and

geo

logi

c ev

olut

ion:

Geo

logi

cal

Soci

ety

of A

mer

ica

Mem

oir

178,

p. 1

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.Po

wel

l, R

.E.,

2001

a, G

eolo

gic

map

and

dig

ital d

atab

ase

of th

e C

onej

o W

ell 7

.5 m

inut

e qu

adra

ngle

, R

iver

side

Cou

nty,

Cal

ifor

nia,

ver

sion

1.0

: U

.S.

Geo

logi

cal

Surv

ey

Ope

n-Fi

le R

epor

t 01-

31, 1

8 p.

, sca

le 1

:24,

000.

http

://ge

opub

s.w

r.usg

s.go

v/op

en-f

ile/o

f01-

31/

Pow

ell,

R.E

., 20

01b,

Geo

logi

c m

ap a

nd d

igita

l da

taba

se o

f th

e Po

rcup

ine

Was

h 7.

5 m

inut

e qu

adra

ngle

, R

iver

side

Cou

nty,

Cal

ifor

nia,

ver

sion

1.0

: U

.S.

Geo

logi

cal

Surv

ey O

pen-

File

Rep

ort 0

1-30

, 18

p., s

cale

1:2

4,00

0.ht

tp://

geop

ubs.

wr.u

sgs.

gov/

open

-file

/of0

1-30

/R

oger

s, J

.J.W

., 19

61, I

gneo

us a

nd m

etam

orph

ic r

ocks

of

the

wes

tern

por

tion

of J

oshu

a T

ree

Nat

iona

l M

onum

ent,

Riv

ersi

de a

nd S

an B

erna

rdin

o C

ount

ies,

Cal

ifor

nia:

C

alif

orni

a D

ivis

ion

of M

ines

Spe

cial

Rep

ort 6

8, 2

6 p.

Stre

ckei

sen

A.,

1976

, To

each

plu

toni

c ro

ck it

s pr

oper

nam

e: E

arth

Sci

ence

Rev

iew

s, v

. 12

, p. 1

-33.

Woo

den,

J.L

., To

sdal

, R

.M.,

How

ard,

K.A

., Po

wel

l, R

.E.,

Mat

ti, J

.C.,

and

Bar

th, A

.P.,

1994

, M

esoz

oic

intr

usiv

e hi

stor

y of

par

ts o

f th

e ea

ster

n T

rans

vers

e R

ange

s,

Cal

ifor

nia:

Pre

limin

ary

U-P

b zi

rcon

res

ults

: G

eolo

gica

l So

ciet

y of

Am

eric

a A

bstr

acts

with

Pro

gram

s, v

. 26,

n. 2

, p. 1

0 4-

105.

You

ng a

lluvi

al d

epos

its,

old

uni

t (H

oloc

ene)

—C

onso

lidat

ed c

oars

e gr

avel

and

sa

nd f

orm

ing

fans

adj

acen

t to

mou

ntai

n-fr

ont

esca

rpm

ents

. O

n co

lor

aeri

al

phot

ogra

phs,

uni

t sh

ows

as d

ark

brow

nish

gra

y to

dar

k gr

ay t

o bl

ack

surf

aces

ch

arac

teri

zed

by p

lum

ose

anas

tom

osin

g ch

anne

ls i

ndic

ativ

e of

bar

and

sw

ale

mor

phol

ogy.

Loc

ally

, un

it in

clud

es c

obbl

y an

d bo

ulde

ry d

ebri

s fl

ow d

epos

its.

Mod

erat

e to

str

ong

varn

ish

on r

ocky

sur

face

s. P

roxi

mal

ly,

unit

is i

nset

int

o P

leis

toce

ne

depo

sits

( Q

oam

3;

Qoa

y);

dist

ally

, it

ov

erla

ps

them

. In

ferr

ed

stra

tigra

phic

pos

ition

, st

rong

des

ert

varn

ish,

and

bar

and

sw

ale

mor

phol

ogy

sugg

est

earl

y H

oloc

ene

age.

Sur

face

s co

rrel

ativ

e w

ith Q

3a s

urfa

ces

of B

ull

(199

1). E

xten

t of

unit

inte

rpre

ted

larg

ely

from

aer

ial p

hoto

grap

hs. I

nclu

des:

You

ng a

lluvi

al d

epos

its,

old

uni

t, g

rave

lly f

acie

s, u

ndiv

ided

(m

iddl

e an

d (o

r) e

arly

Hol

ocen

e)—

Gra

velly

allu

vium

for

min

g fe

eder

-cha

nnel

dep

osits

in

cany

on-b

otto

ms

and

fan

depo

sits

pro

xim

al t

o st

eep

rang

e fr

onts

on

clas

s 1

pied

mon

ts. O

n so

me

fans

, tw

o se

quen

ces

can

be d

istin

guis

hed

mor

phol

ogic

ally

. L

ocal

ly, d

ivid

ed in

to:

You

ng a

lluvi

al d

epos

its,

old

uni

t, g

rave

lly f

acie

s 2—

You

nger

seq

uenc

e of

co

arse

gra

velly

allu

vial

dep

osits

. At

a fe

w l

ocal

ities

, ea

rly

fan

depo

sits

can

be

dist

ingu

ishe

d in

thi

s se

quen

ce o

n th

e ba

sis

of a

rou

gher

sur

face

tex

ture

as

seen

on

col

or a

real

pho

togr

aphs

. L

ocal

ly, c

onta

ins:

You

ng

allu

vial

d

epos

its,

ol

d

un

it,

grav

elly

fa

cies

2,

ro

ugh

su

rfac

e—C

oars

est

and

mos

t pr

oxim

al p

arts

of

unit

2 th

at d

ispl

ay a

n es

peci

ally

ro

ugh

surf

ace

text

ure

on a

eria

l ph

otog

raph

s; t

extu

re r

efle

cts

high

-rel

ief

bar

and

swal

e m

orph

olog

y as

soci

ated

with

ext

rem

ely

coar

se g

rave

l or

rew

orke

d de

bris

You

ng a

lluvi

al d

epos

its,

old

uni

t, g

rave

lly f

acie

s 1—

Old

er s

eque

nce

of

coar

se g

rave

lly a

lluvi

al d

epos

its. A

t a

few

loc

aliti

es,

earl

y fa

n de

posi

ts c

an b

e di

stin

guis

hed

in t

his

sequ

ence

on

the

basi

s of

a r

ough

er s

urfa

ce t

extu

re a

s se

en

on c

olor

are

al p

hoto

grap

hs.

Loc

ally

, con

tain

s:Y

oun

g al

luvi

al

dep

osit

s,

old

u

nit

, gr

avel

ly

faci

es

1,

rou

gh

surf

ace—

Coa

rses

t an

d m

ost

prox

imal

par

ts o

f un

it 1

that

dis

play

a r

ough

su

rfac

e te

xtur

e on

aer

ial

phot

ogra

phs;

tex

ture

ref

lect

s hi

gh-r

elie

f ba

r an

d sw

ale

mor

phol

ogy

asso

ciat

ed w

ith e

xtre

mel

y co

arse

gra

vel o

r re

wor

ked

debr

is

YO

UN

G A

ND

OL

D(?

) SU

RF

ICIA

L D

EP

OSI

TS

You

ng a

lluv

ial

depo

sits

, ol

d ox

idiz

ed s

andy

uni

t (m

iddl

e an

d (o

r) e

arly

H

oloc

ene

and

late

Ple

isto

cene

?)—

Sand

and

peb

bly

to c

obbl

y sa

nd f

orm

ing

apro

ns o

n m

ount

ain-

fron

t an

d in

selb

erg

pied

mon

ts w

here

sou

rce

terr

ane

cons

ists

of

C

reta

ceou

s gr

anit

ic

rock

s. T

hick

est

whe

re

butt

ress

ed

agai

nst

inse

lber

gs

or

rang

e-fr

ont;

ta

pers

do

wn-

pied

mon

t in

to

thin

ve

neer

s on

Pl

eist

ocen

e de

posi

ts.

Whe

re u

nit

is e

xpos

ed i

n ar

royo

wal

ls h

igh

on p

iedm

ont

slop

es, l

oose

sur

fici

al s

edim

ent p

asse

s do

wn-

sect

ion

into

fir

mer

slo

pe w

ash

and

allu

vial

dep

osits

. D

epos

its o

f th

is u

nit

redd

en w

ith d

epth

and

pro

babl

y co

ntai

n on

e or

mor

e bu

ried

soi

l ho

rizo

ns.

In p

lace

s, r

edde

ned

sedi

men

t co

ntai

ns

scat

tere

d eq

uant

ble

bs o

f fi

lam

ento

us c

alci

te,

indi

catin

g an

inc

ipie

nt (

Stag

e I)

ca

lcic

soi

l. U

nit

surf

aces

are

sm

ooth

, sa

ndy,

and

cha

ract

eriz

ed b

y ox

idiz

ed

grai

ns o

f po

tass

ium

fel

dspa

r th

at r

ange

in

colo

r fr

om r

eddi

sh y

ello

w (

5YR

6/6

to

7/6

) to

yel

low

ish

red

(5Y

R 5

/6)

to p

ink

(5Y

R 7

/4);

app

ear

oran

ge o

n co

lor

aeri

al p

hoto

grap

hs.

The

se g

rain

s oc

cur

as v

enee

r un

derl

ain

by p

edog

enic

Av

hori

zon

of l

oess

-lik

e, v

esic

ular

ver

y pa

le b

row

n (1

0YR

7/3

) ca

lcar

eous

silt

, ty

pica

lly 1

to

4 cm

thi

ck.

Av

hori

zon

unde

rlai

n by

pal

e-br

own

(10Y

R 6

/3 t

o 6.

5/3)

to

light

yel

low

ish-

brow

n (1

0YR

6/4

) sa

nd. U

nit

infe

rred

to

incl

ude

late

st

Plei

stoc

ene

and

(or)

ear

ly to

mid

dle

Hol

ocen

e ag

grad

atio

nal a

lluvi

al d

epos

its a

s w

ell

as y

oung

er a

lluvi

al d

epos

its t

hat

have

acc

umul

ated

as

a re

sult

of s

heet

fl

oods

ori

gina

ting

eith

er a

s dr

aina

ge b

asin

dis

char

ge o

r as

sur

face

run

-off

acr

oss

the

olde

r de

posi

ts. P

roxi

mal

par

ts o

f un

it ar

e in

cise

d by

cha

nnel

s in

whi

ch m

ore

rece

nt y

oung

(Q

yam

uni

ts a

nd Q

yay

units

) an

d ve

ry y

oung

(Q

vya

units

) al

luvi

al

depo

sits

hav

e ac

cum

ulat

ed. D

own-

pied

mon

t, w

here

mor

e re

cent

you

ng d

epos

its

feat

her

out

onto

Qya

os,

Qya

os s

urfa

ces

are

slig

htly

dis

sect

ed b

y an

asto

mos

ing

netw

ork

of b

raid

ed c

hann

els

surr

ound

ing

smal

l is

land

s of

Qya

os. U

nit

typi

cally

oc

curs

as

thin

allu

vial

apr

on d

epos

ited

on w

eath

ered

gra

nitic

bas

emen

t hi

gh o

n pi

edm

ont

slop

es a

nd s

prea

d do

wn-

slop

e ac

ross

old

er s

urfi

cial

dep

osit

s. A

s m

appe

d, u

nit m

ay in

clud

e m

ore

rece

nt y

oung

dep

osits

YO

UN

G A

ND

(O

R)

OL

D S

UR

FIC

IAL

DE

PO

SIT

SC

ollu

vial

de

posi

ts,

undi

vide

d (Q

uate

rnar

y)—

Col

luvi

al

apro

ns

shed

fr

om

crys

tall

ine

base

men

t es

carp

men

ts

alon

g ca

nyon

w

alls

an

d ra

nge-

fron

ts;

pred

omin

antly

talu

s

OL

D

SUR

FIC

IAL

D

EP

OSI

TS—

Con

soli

date

d de

posi

ts

in

allu

vial

fa

ns,

on

pied

mon

t sl

opes

, an

d in

col

luvi

al d

ebri

s ap

rons

. O

ld d

epos

its e

xhib

it sl

ight

ly t

o st

rong

ly d

isse

cted

geo

mor

phic

sur

face

s; g

rave

lly d

epos

its h

ave

wel

l-de

velo

ped

and

stro

ngly

var

nish

ed p

avem

ents

; gr

aniti

c de

bris

cha

ract

eriz

ed b

y A

v/B

t/Bk/

Cox

soi

l pr

ofile

s; S

tage

III

-IV

car

bona

te m

orph

olog

y. T

hese

dep

osits

mer

ge w

ith o

ne a

noth

er

to f

orm

a th

in m

antle

that

for

med

on

an e

volv

ing

Plei

stoc

ene

land

scap

eO

ld

allu

vial

de

posi

ts

(Hol

ocen

e?

and

Ple

isto

cene

)—C

onso

lida

ted

allu

vium

de

posi

ted

in c

anyo

n an

d ar

royo

bot

tom

s an

d on

pie

dmon

t sl

opes

. A

s w

ith

youn

g al

luvi

al d

epos

its (

Qya

uni

ts),

old

pie

dmon

t al

luvi

al d

epos

its c

ompr

ise

two

clas

ses:

(1)

Dep

osit

s th

at o

ccur

in

allu

vial

apr

ons

char

acte

rize

d by

pr

omin

ently

con

e-sh

aped

, m

ulti-

lobe

d fa

ns t

hat

coal

esce

int

o ba

jada

s do

wn-

pied

mon

t. S

edim

ents

ge

nera

lly

have

a

sour

ce

in

resi

stan

t ro

cks

havi

ng

wea

ther

ing

and

denu

dati

on c

hara

cter

isti

cs t

hat

are

rela

tivel

y in

sens

itiv

e to

cl

imat

ic c

hang

e (s

ee B

ull,

1991

, p.

161

-167

). S

and

and

grav

el.

Uni

t su

rfac

es

cons

ist

of v

ery

wel

l-de

velo

ped

pave

men

ts o

f st

rong

ly v

arni

shed

peb

bles

and

co

bble

s; d

ark

and

smoo

th.

Pave

men

ts u

nder

lain

by

pedo

geni

c A

v ho

rizo

n of

ve

ry p

ale

brow

n (1

0YR

7/3

), l

oess

-lik

e, v

esic

ular

silt

. R

elic

t pa

vem

ents

and

un

derl

ying

old

allu

vial

dep

osits

are

mor

e de

eply

dis

sect

ed w

ith i

ncre

asin

g ag

e.

(2)

Dep

osits

tha

t oc

cur

on b

road

pie

dmon

t sl

opes

dev

elop

ed o

n re

lativ

ely

less

re

sist

ant

rock

s al

ong

deep

ly

emba

yed

mou

ntai

n fr

onts

. W

eath

erin

g an

d de

nuda

tion

char

acte

rist

ics

of th

ese

less

res

ista

nt r

ocks

are

rel

ativ

ely

sens

itive

to

clim

atic

cha

nge.

In

Pin

to M

ount

ain

quad

rang

le,

clas

s 2

pied

mon

t de

posi

ts

cons

ist

of c

onso

lida

ted

allu

vium

and

slo

pe w

ash

that

acc

umul

ated

as

thin

ap

rons

on

pedi

men

ts b

evel

ed o

nto

Mes

ozoi

c gr

aniti

c ro

cks,

Pro

tero

zoic

gra

nite

gn

eiss

of

Josh

ua T

ree,

and

Qua

tern

ary

and

(or)

Ter

tiary

str

ata.

The

und

erly

ing

crys

talli

ne r

ocks

are

exp

osed

sou

th o

f th

e qu

adra

ngle

, w

here

allu

vial

uni

ts a

re

buttr

esse

d ag

ains

t ba

ses

of i

nsel

berg

s in

the

Eag

le M

ount

ains

(se

e In

dex

Map

).

Muc

h of

map

ping

of

thes

e de

posi

ts is

bas

ed o

n ae

rial

pho

togr

aph

inte

rpre

tatio

n an

d ha

s no

t bee

n fi

eld-

chec

ked;

age

ass

ignm

ents

are

tent

ativ

e. C

onsi

sts

of:

Old

allu

vial

dep

osit

s, y

oung

uni

t (H

oloc

ene?

and

lat

e P

leis

toce

ne)—

Sand

and

pe

bbly

to

cobb

ly s

and

depo

site

d as

allu

vial

fill

in

cany

ons

and

arro

yos

and

in

apro

ns b

uttr

esse

d ag

ains

t ba

ses

of i

nsel

berg

s an

d m

ount

ain

mas

sifs

. D

epos

its

chie

fly

deri

ved

from

ex

posu

res

of

gran

ite

gnei

ss

of

Josh

ua

Tre

e an

d m

onzo

dior

ite

of M

unse

n C

anyo

n so

uth

of q

uadr

angl

e (s

ee P

owel

l, 20

01a,

20

01b)

. Pa

vem

ents

are

lig

ht-c

olor

ed,

smoo

th,

and

mod

erat

ely

inci

sed

by

dend

riti

c ne

twor

ks o

f cl

osel

y sp

aced

gul

lies

gen

erat

ed b

y su

rfac

e ru

n-of

f.

Dep

osits

par

tially

bur

y ol

der

eros

iona

l la

ndsc

ape

on w

hich

ped

imen

t fl

atir

ons

had

deve

lope

d on

ear

lier

allu

vial

-slo

pe a

pron

s D

epos

its i

nset

int

o Q

oam

uni

ts.

As

map

ped,

may

inc

lude

old

er Q

oam

uni

ts h

avin

g at

ypic

ally

lig

ht-c

olor

ed

pave

men

tO

ld a

lluvi

al d

epos

its,

mid

dle

unit

, un

divi

ded

(Ple

isto

cene

)—Sa

nd a

nd g

rave

l. S

urfa

ces

cons

ist

of v

ery

wel

l-de

velo

ped

pave

men

ts o

f st

rong

ly v

arni

shed

pe

bble

s an

d co

bble

s; s

urfa

ces

are

dark

and

sm

ooth

. Pa

vem

ents

und

erla

in b

y pe

doge

nic

Av

hori

zon

of v

ery

pale

bro

wn

(10Y

R 7

/3),

loe

ss-l

ike,

ves

icul

ar s

ilt.

Rel

ict

pave

men

ts

and

unde

rlyi

ng

old

allu

vial

de

posi

ts

are

mor

e de

eply

di

ssec

ted

with

incr

easi

ng a

ge. I

nclu

des:

Mid

dle

unit

3 (

late

Ple

isto

cene

)—Sa

nd a

nd g

rave

l. Pa

vem

ents

are

gen

eral

ly

cont

inuo

us o

ver

broa

d re

lict

sur

face

s; s

ligh

tly

to m

oder

atel

y in

cise

d by

de

ndri

tic n

etw

ork

of s

catte

red

to c

lose

ly s

pace

d gu

llies

. Dep

osits

are

ins

et i

nto

exta

nt o

ld a

nd v

ery

old

allu

vial

dep

osits

(Q

oam

2; Q

voa)

Mid

dle

unit

2 (

mid

dle?

Ple

isto

cene

)—Sa

nd a

nd g

rave

l. Pa

vem

ents

ext

rem

ely

dark

; m

oder

atel

y to

dee

ply

inci

sed

by d

endr

itic

netw

ork

of g

ullie

s. P

avem

ent

and

Av

hori

zon

unde

rlai

n by

red

dene

d pe

doge

nic

B-h

oriz

on, i

n tu

rn u

nder

lain

Qya

u

QT

su

Qvo

a

Jmiu

SUR

RO

UN

DIN

G 7

.5' Q

UA

DR

AN

GL

ES

DE

SCR

IPT

ION

OF

MA

P U

NIT

S1

45

Stri

ke a

nd d

ip o

f fl

ow b

eddi

ng in

sed

imen

tary

str

ata

I

nclin

ed

49

Stri

ke a

nd d

ip o

f fo

liati

on a

nd la

yeri

ng in

met

amor

phic

roc

ks

I

nclin

ed

Ver

tica

l

Bea

ring

and

plu

nge

of m

inor

fold

axi

s an

d pa

ralle

l lin

eati

on

Bea

ring

and

plu

nge

of s

tret

ched

-peb

ble

linea

tion

Bea

ring

and

plu

nge

of a

ligne

d-m

iner

al li

neat

ion

35

Qvy

a 2

Qvy

ye

Qvy

a 1

Tb

Jsbp

CA

LIF

AR

EA

OF

MA

P

Con

tact

—S

olid

whe

re l

ocat

ion

mee

ts m

ap a

ccur

acy

stan

dard

(w

ithi

n 40

ft

or 1

2 m

); d

ashe

d w

here

ap

prox

imat

ely

loca

ted,

may

not

mee

t m

ap a

ccur

acy

stan

dard

; dot

ted

whe

re c

once

aled

Fac

ies

boun

dary

—In

tra-

unit

bou

ndar

y th

at s

epar

ates

al

luvi

al d

epos

its

deri

ved

from

dif

fere

nt d

rain

ages

. A

ppro

xim

atel

y lo

cate

d, m

ay n

ot m

eet

map

acc

urac

y st

anda

rd

Fau

lt—

Hig

h an

gle,

obs

erve

d or

inf

erre

d. S

olid

whe

re

loca

tion

mee

ts m

ap a

ccur

acy

stan

dard

(w

ithin

40

ft

or 1

2 m

); d

ashe

d w

here

app

roxi

mat

ely

loca

ted,

may

no

t m

eet

map

ac

cura

cy

stan

dard

; do

tted

w

here

co

ncea

led

Fau

lt—

Low

ang

le, i

nfer

red.

App

roxi

mat

ely

loca

ted,

may

no

t mee

t map

acc

urac

y st

anda

rd

Fau

lt-l

ine

scar

p

Cla

ssif

icat

ion

of p

luto

nic

rock

type

s (f

rom

Str

ecke

isen

, 197

6).

A, a

lkal

i fel

dspa

r; P

, pla

gioc

lase

fel

dspa

r; Q

, qua

rtz.

Qua

rtz

Syen

iteQ

uart

zM

onzo

nite

Qua

rtz

Mon

zodi

orite

Syen

iteM

onzo

nite

Mon

zodi

orite

Gra

nite

Alkali-feldspar G

ranite

Tonalite

Dio

rite

Syenogranite

Granodiorite

Monzogranite

Quartz

Diorite

9065

3510

5

20

60Q

Q

AP

60

20

5

60

The

mat

rix

colo

r of

sur

fici

al m

ater

ials

and

thei

r pe

doge

nic

soils

is

cla

ssif

ied

acco

rdin

g to

the

Mun

sell

soil-

colo

r ch

arts

(M

unse

ll, 1

975)

.

Thi

s re

port

is

prel

imin

ary

and

has

not

been

rev

iew

ed f

or c

onfo

rmity

with

U.S

. Geo

logi

cal

Surv

ey

edito

rial

sta

ndar

ds o

r w

ith t

he N

orth

Am

eric

an S

trat

igra

phic

Cod

e. A

ny u

se o

f tr

ade,

pro

duct

, or

fi

rm n

ames

is

for

desc

ript

ive

purp

oses

onl

y an

d do

es n

ot i

mpl

y en

dors

emen

t by

the

U.S

. G

over

nmen

t.

Pin

toM

ount

ain

7.5'

Was

hingto

nW

ash

Con

ejo

W

ell(O

F 01-3

1)

New D

ale

San B

ernard

ino

Was

h(O

F 02-4

98)

Fried L

iver

Was

h

Porcu

pine

Was

h(O

F 01-3

0)

Humbu

gM

tn.

Twentyn

ine

Palm

s Mou

ntain

Ts

Jmid

Qcu

Qya

yu

Qya

mu

Qya

ms

Qya

yg

Qya

ys

Qya

mgu

QT

pbl

QT

pbs

QT

pbd

Qoa

m3

Qoa

y

Qya

mg2

Unc

onfo

rmity

Qya

mg1

Qya

og1

Qya

ogu

Qya

os

Qya

og2r

Qya

og2

Qya

og1r

Qoa

m1

Qya

ss

TJh

TJh

QT

cq

Qoa

m2

Allu

vial

dep

osits

Unc

onfo

rmity

(pe

dim

ent)

Unc

onfo

rmity

(pe

dim

ent)

Unc

onfo

rmity

(pe

dim

ent)

Qoa

y

CO

RR

EL

AT

ION

OF

MA

P U

NIT

S1

Tb

QT

su

Qvo

a

Hol

ocen

e

Plei

stoc

ene

CE

NO

ZO

IC

Plio

cene

Mio

cene

TE

RT

IAR

Y

QU

AT

ER

NA

RY

CR

ET

AC

EO

US

JUR

ASS

IC

ME

SOZ

OIC

Qoa

m2

Qoa

m1

Qya

os

Unc

onfo

rmity

(pe

dim

ent)

Unc

onfo

rmity Jm

iu

Qvy

a 2

Qoc

u

Qvy

auQ

vya 1

Qoa

m3

Qya

u

Qoa

mu

PRO

TE

RO

ZO

IC

Plut

onic

roc

ks(E

aste

rn b

elt)

Surf

icia

l dep

osits

Hyp

abys

sal i

ntru

sive

roc

ksan

d di

kes

Met

amor

phic

roc

ks

Col

luvi

al d

epos

its

TJd

u

TJd

u

GE

OL

OG

IC M

AP

AN

D D

IGIT

AL

DA

TA

BA

SE O

F T

HE

PIN

TO

MO

UN

TA

IN 7

.5' Q

UA

DR

AN

GL

E,

RIV

ER

SID

E C

OU

NT

Y, C

AL

IFO

RN

IA

Prep

ared

in c

oope

ratio

n w

ith th

eN

AT

ION

AL

PA

RK

SE

RV

ICE

and

CA

LIF

OR

NIA

GE

OL

OG

ICA

L S

UR

VE

YU

.S. D

EPA

RT

ME

NT

OF

TH

E I

NT

ER

IOR

U.S

. GE

OL

OG

ICA

L S

UR

VE

Y

Qvy

au

Eol

ian

depo

sits

Was

hde

posi

ts

Qoc

u

Play

ade

posi

ts

Qya

mu

Qya

yuQ

yayg

Qya

mgu

Qoc

2

Qoc

1

Qya

ms

Relativeageandstratigrapicrelationsuncertain

Relative age and stratigraphic

relations uncertain

Jpw

Qya

ssQ

yays

Qya

mg1

Qya

ogu

Qya

og2

Qya

og1

Qya

mg2

Qya

og1r

Qya

og2r

Qoc

2

Qoc

1

Qcu

Jsbp

Unmetamorphosed cover

Surf

icia

l dep

osits

Surficial deposits Surficial deposits Crystalline basement

QT

cq

Jmid

QT

pbc

QT

pbl

QT

pbc

QT

pbs

QT

pbd

PA

RK

PIN

TO

MO

UN

TA

INS

EA

GL

EM

OU

NTA

INS

HEXIE

MO

UN

TA

INS

LIT

TL

ES

AN

BE

RN

AR

DIN

OM

OU

NT

AIN

S

PIN

TO

BA

SIN

COXCOMBMOUNTAIN

S

CH

UC

KW

AL

LA

VA

LL

EY

CH

UC

KW

AL

LA

MO

UN

TA

INS

CH

OC

OL

AT

E

MO

UN

TA

INS

OR

OC

OP

IAM

OU

NT

AIN

S

MO

JA

VE

DE

SE

RT

Da

le

L

ak

e

Sa

lto

n Se

a

Ha

yfie

ld

La

ke

Pa

le

nL

ak

e

Red

But

teW

ash

Fo

rd

D

ry

La

ke

Yu

cc

aV

alle

y

Jo

sh

ua

Tr

ee

Tw

en

ty

nin

eP

alm

s

Mo

ro

ng

oV

alle

y Pa

lm

Sp

rin

gs

In

dio

Me

cc

a

Ch

ir

ia

co

Su

mm

it

De

se

rt

Ce

nte

r

Cot

tonw

ood

Pass

1

16

˚00

' 1

15

˚30

' 1

16

˚30

' 1

15

˚00

'

3

4˚0

0'

3

3˚3

0'

0

5

10

km

0

5

10

mi

62

62

COAC

HE

LL

AVA

LL

EY

10 In

dex

Map

Munsen Canyon

Pink

ham

Big

Was

h

Mon

umen

tM

ount

ain

Pint

oM

ount

ain

Wils

onC

anyo

n

E A

S T

E R

N

T R

A N

S V

E R

S E

R A

N G

E S

S A

L T

O N

T R

O U

G H

LITT

LE C

HU

CK

WA

LLA

MO

UN

TAIN

S

CO

LO

RA

DO

DE

SE

RT

Ea

gle

Mo

un

ta

in

x

Iron

Chi

efm

ine

XX X

X

Eag

le M

ount

ain

min

eX

XBla

ckE

agle

min

e

Placer

NA

TI

ON

AL

Pint

o

Was

h

JO

SH

UA

TR

EE

CO

TT

ON

WO

OD

MO

UN

TA

INS

Canyon

Was

h

N

Pin

to

Mo

un

tain

qu

ad

ran

gle

Qvy

yeQ

vyyp

Qvy

yp

Jpw

28

Dis

cont

inuo

us Q

vyye

ven

eer

on m

appe

d un

it

Dis

cont

inuo

us Q

vyye

and

Qoc

u ve

neer

s on

map

ped

unit

Dis

cont

inuo

us Q

ocu

vene

er o

n m

appe

d un

it

SUR

FIC

IAL

VE

NE

ER

S

Con

tinuo

us Q

yam

s ve

neer

on

unde

rlyi

ng Q

yaos

uni

t

1 U.S

. Geo

logi

cal S

urve

y90

4 W

. Riv

ersi

de A

venu

e, R

oom

202

Spok

ane,

WA

992

01

Ver

sion

1.0

by R

ober

t E

. Pow

ell1

Dig

ital

pre

para

tion

by

Pam

ela

M. C

osse

tte1

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