24 July 1981, Volume 213, Number 4506

Prehistoric Raised-FAgriculture in the Maya Lowla

B. L. Turner II and Peter D. HI;

Research during the 1970's indicatedthat the prehistoric Maya of the Yucatanpeninsular region employed a variety oftechnologies indicative of intensive agri-culture, such as terraces (1, 2), raisedfields (1, 3-5), and, possibly, dryland

monolevel platform N

nals to control waterrooting layer and plaihydraulic manipulati4irrigation is generall3tion with numerous

Summary. The ground pattems found in Pulitrouser Swamp, nvestiges of raised and channelized fields, types of wetland cultilancient Maya. This form of hydraulic cultivation was apparently ebetween 200 B.C. and A.D. 850. The environment of the swacanals, and one nearby settlement, Kokeal, are described. Thethat the large number of well-defined ground patterns reported incentral Maya lowlands are probably vestiges of Maya wetland cu

irrigation (6). The initial evidence of theuse of raised fields by the Maya generat-ed controversy and challenges becauseinterpretations were based largely on ae-rial identification of the features andbecause the aerial extent of the projectedfields suggested that the Maya were en-gaged in large-scale hydraulic cultiva-tion. In turn, the scale introduced thepossibility of centralized sociopoliticalcontrol (7).A raised field is an agricultural feature

created by transferring earth to raise anarea above the natural terrain (8). Fieldmorphologies, which vary, are largelyrelated to the special function or func-tions of the field (9). For example, ininundated zones the raised field may be a

B. L. Turner II is an associate professor in theGraduate School of Geography, Clark University,Worcester, Massachusetts 01610; Peter D. Harrisonis an adjunct professor in the Department of Anthro-pology, University of New Mexico, Albuquerque87106. The authors were affiliated with the Depart-ment of Geography, University of Oklahoma, andthe Middle American Research Institute, TulaneUniversity, respectively, during the study.

SCIENCE, VOL. 213, 24 JULY 1981

dures to sustain inten9). In Mesoamerica,the Basin of Mexico E

monolevel platform t!some have been in insince the Spanish Co

Vestiges of raisedlowlands were first diCandelaria Basin ofpeche (3). Examinati(confirmed that there200 hectares of fielhabitat (3, 11). Largerwere later identified idepression (bajo) haBelize and southern (ico, including Pulltroiaerial observationsSiemens (11) projectznearly 3200 hectares (

Belize alone; ground (

ever, were limited tialong the Hondo RiveSan Antonio, Albion1) (12). Other res

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ground and vegetation patterns indica-tive of raised fields in the large depres-sions of southern Quintana Roo (1, 5).These features, conservatively estimatedto cover 400 square kilometers in Quinta-na Roo, were identified solely by- aerial

'ield reconnaissance and photography (13).The existence of relic complexes of

inds raised fields identified from the air alonehas been questioned (14). It was suggest-ed that many of the finds, particularly

amKT1sonl the extensive patterns in southern Quin-tana Roo, could be gilgai, a natural for-mation resulting from seasonal extremesin the moisture content of expansible

with associated ca- clays. Large surface cracks developr levels around the when the clays desiccate; when wet, thenting surface. Such infilling material swells, and this pro-

on for drainage or motes lateral and upward pressures thaty used in conjunc- may result in a variety of regular groundcultivation proce- patterns (15). In addition, pedological

work near San Antonio (Fig. 1) hasraised questions about interpretations

iorthem Belize, are from ground studies which indicated thativation used by the raised fields occurred there (16). It wasImployed sometime suggested that the surface features wereimp, the fields and naturally alluviated deposits that appearevidence indicates to be raised because a network of canalsother areas in the or channels had been cut through the

iltivation. area, apparently creating channelizedfields. The existence of channelizedfields has been supported by work on

isive agriculture (8, similar surface patterns along Barberthe chinampas of Creek, near Lamanai (17) (Fig. 1).

are examples of the Several issues related to the use ofype of raised fields; raised-field agriculture by the prehistoricitensive production Maya were investigated during the 1979Inquest (10). Pulltrouser Swamp Project (18). Becausefields in the Maya it was assumed that true raised fieldsvscovered in the Rio were most likely to occur in interiorlysoutheastern Cam- drained depressions, the project focusedDn of these features on the identification of such features atwere about 150 to one locale. The habitat in which theIs in that riverine features occur and Maya settlementsrareas of relic fields near the depression were also studied.in both riverine and The project's findings are summarized inLbitats in northern this article.2uintana Roo, Mex-user Swamp. Fromand photography, The Study Areaed the existence ofof fields in northern The eastern peripheries of the centralexaminations, how- Maya lowlands in northern Belize ando riverine habitats southeastern Quintana Roo are part of-r, particularly near the flat, low-lying coastal margin of theIsland, Belize (Fig. limestone shelf known as the Yucatan;earchers reported Peninsula (Fig. 1). The terrain is karst.

0036-8075/81/0724-0399$01.75/0 Copyright © 1981 AAAS 399

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The mean annual precipitation in thiszone ranges from about 1400 millimetersin the north to 2000 millimeters in thesouth, but annual totals vary considera-bly [W.C.J.; see (18)]. Rainfall is season-al, with a distinct dry season from Febru-ary through April or mid-May.At least two topographic zones, river-

ine lands and depressions, in the easternperipheries of the lowlands are prone toseasonal or permanent inundation (19).Riverine lands, confined to narrowbands along the rivers, such as the Hon-do and New, rarely desiccate. Depres-sions are either interiorly drained ormaintain slow outward or subterraneandrainage. They are locally referred to asbajos, akalches, savannas, swamps, ormarshes, depending on their size, theseverity of inundation, or the type ofvegetation (20). Depressions are more

common features in the area than areriverine lands.The eastern riverine-depression zone

of the central Maya lowlands was dense-ly inhabited in prehistoric times. Rem-nants of Maya settlements stretch fromnorth of Tzibanche, Kohunlich, and Nic-olas Bravo to Lamanai in the south (Fig.1). Ruins are especially abundant alongthe corridor between the Hondo andNew rivers, beginning at Cerros, at theBahia de Chetumal, and including Aven-tura, Louisville, Nohmul, Cuello, and ElPosito. The area was apparently occu-pied very early in Maya prehistory. Aseries of radiocarbon dates from Cuellorange from 3200 to 200 B.C. (21). Theceramic styles associated with the earlydates at Cuello are found elsewhere inthe corridor, suggesting that the earlyoccupation was not limited to one site.

Ground patterns thought to representvestiges of raised fields and canals havebeen identified in a large number ofdepressions in this zone (1, 4, 5, 11, 12).At least two distinctive ground patternsare prevalent: quadrilateral shapes inpaired rows (Fig. 2) and quadrilateral toamorphous shapes in sectional or grouppatterns (Fig. 3). Pulltrouser Swamp wasselected for study because it (i) containsboth ground patterns, (ii) has a variety ofbio-hydrological zones that are compara-ble to those found in virtually everydepression in the area that has beenreported to have raised fields, (iii) is nearseveral major Maya centers, and (iv) isaccessible.

Habitat

Pulltrouser Swamp is a large, Y-shaped depression located about 4.5 kmnorth of Orange Walk Town, Belize. Itsthree major arms cover an area of about8.5 kM2: there are about 3.6 km2 inPulltrouser South, 2.9 km2 in PulltrouserEast, and 2.0 km2 in Pulltrouser West(Fig. 4). Surface water is captured asrunoff from the higher ground or ridge-land corridor to the west and drains veryslowly from the two northern arms intothe southern arm. Most of the area of theeastern and southern arms retains somewater throughout the year, although onlyinterior ponds may retain surface waterduring severe droughts. The occurrencein the southern arm of several species offreshwater gastropods, including theprosobranch Pyrgophorous coronatus,suggests that a large volume of well-oxygenated surface water is regularlypresent in the depression (A.C.). Be-cause water levels fluctuate along theborders of the eastern and southernarms, the sediment-filled channels near-est the swamp-mainland border tend todry annually, and an amphibious speciesof gastropod, Pomacea flagellata, isdominant. The higher lying western armhas a greater annual range of water lev-els. About I meter of surface water maystand in the western arm during the wetseason. However, dry season surfacewater is limited to several interior ponds,and the water table throughout most ofthe western arm is found at depths ex-ceeding 1 m.These varying hydrologies produce

distinct types of vegetation. The deeperand more stable water levels in the interi-ors of the eastern and southern armssupport a sawgrass marsh. Toward themargins of the depression, but within themarsh zone, the mounds that producethe ground patterning are marked by

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Fig. 1. Map of the wetlands of the eastern peripheries of the central Maya lowlands.

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Fig. 2 (left). Paired-row ground pattern created by relic wetland (raised?) fields at Long Swamp, northern Belize. Fig. 3 (right). Sectionalground pattern created by relic raised fields at the north end of the eastern arm of Pulltrouser Swamp. The fields extend into the escoba-botan for-est. The larger fields are 30 to 35 m in length. Palmettos grow in the nonforested fields.

stands of palmettos or small palms,Acoelorraphe sp. (Fig. 3). The moundscontinue toward the mainland-depres-sion border for a distance of 80 to 150 m.These mounds are not visible from theair because they are obscured by a tallswamp or escoba-botan forest, charac-terized by the bully (or bullet) tree (Bu-cida bursera), chechem (Metopiumb,ownei), and various palms such asescoba (Cryosophila argentea) thatflourish on the mounds. Pulltrouser Westis dominated by a shortgrass savanna,with the exception of an interior pondzone that is surrounded by mounds cov-ered with an escoba-botan forest. Thesavanna is associated with severe sea-sonal fluctuations in water levels.The soils of the mound and savanna

zones are mollisols, belonging to thesubgroups cumulic and vertic hapla-quolls, respectively (J.P.D.). They arepredominantly silt and contain smallamounts of montmorillonite clay (22). Inundisturbed conditions, a solum restsdirectly on weathered limestone or sas-cab (23). The light-colored sascab isfound at depths ranging to 50 centimeterson the mainland border of the depressionand to 100 centimeters in undisturbedsections of the depression proper (24).The data provide several clues to the

conditions of the depression from Mayaoccupance to modern times. The fossilpollen indicates that PuHltrouser Southmay have been dominated more by themarsh habitat in the past (F.M.W.), andthe molluscan remains suggest that thedepression rarely, if ever, desiccates(A.C.). The degree of water level fluctu-ations within the ground pattern zone inthe past is uncertain, although seasonalfluctuations apparently occurred (25).The extension of the escoba-botan forest

into the depression is apparently a re-sponse to the presence of the mounds.Pulltrouser South appears to have beensimilar in terms of surface water charac-teristics to the swamp-lakes of Chalcoand Xochimilco in the Basin of Mexicoat the time when the chinampa systemwas constructed by the pre-Hispanic oc-cupants of the basin (10). Climaticchanges that may have taken place dur-ing Maya times have not yet been docu-mented at Pulltrouser Swamp, nor at thistime has evidence been found in theswamp of major sedimentation that hasbeen recorded in the more rugged Petdnof Guatemala (26).

Ground Pattern Study

About 311 ha of well-defined groundpatterns are visible along the edges ofPulltrouser South and East and in thesouthern interior of Pulltrouser West(Fig. 3). Less distinctive patterns coveran additional 357 ha of some of theinterior portions of Pulltrouser Southand East (27). The well-defined patternsare located principally along the main-land edge, which rises about 1 m abovethe depression, and along the exteriorportions of the depression proper.Three sites were selected for study.

Sites 1 and 2 were located along thesouth central portion of the western sideof Pulltrouser South, and site 3 wassituated at the base or southern end ofPulltrouser East, where it connects withPulltrouser South. Twenty-nine unitswere excavated in various mounds at thethree locations. In addition, numeroussoil pits were dug and samples takenwith a bucket auger in the pits and atother locations, including the shortgrass

24 JULY 1981

savanna and the mounds in the interiorof Pulltrouser West. Mounds situatedalong the mainland edge in the escoba-botan forest and on the edge of the marsh(mounds with palmettos) were excavat-ed. The studies demonstrate that themounds of the ground pattern zones atPulltrouser Swamp are vestiges of chan-nelized and raised fields and associatedcanals built by the ancient Maya. Chan-nelized or border fields, which are situat-ed along the mainland edge of the de-pression (Fig. 5), were created by theconstruction of short canals, generallynot exceeding 10 to 20 m in length and 2to 3 m in width, that connect the depres-sion with the mainland. Major field rais-ing was apparently not involved withthese features (Fig. 6). Soil profiles re-veal a solum of about 30 to 50 cm, restingon sascab. Artifacts were found in thesolum and on the solum-sascab contact,but were not in the sascab zone. Theinland canals had been cut as deep as 1 minto the sascab.True raised or island fields are located

in the depression proper, often in a lineor other symmetrical arrangement withthe adjacent channelized fields (Fig. 5).Raised fields are elaborate constructions(Fig. 6) and are more numerous than thechannelized fields. They comprise about90 percent of the total area known tocontain relic fields and canals. A solum,30 to 50 cm thick, rests on gray fillmaterial that is about 100 cm thick and isspeckled with small, angular fragmentsof limestone. In most excavations thismaterial rests directly on sascab, butseveral soil sample cores taken at raisedfield site 1 (Fig. 5) revealed a 20-cm-thickdeposit of black soil with abundantaquatic remains; this soil was interpretedas part of the original depression topsoil.

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The intervening canals have been cut asdeep as 100 cm into the underlying sas-cab. Artifacts were found in the solumand fill material and in the canal sedi-ments. No cultural remains were locatedin the black layer or in the sascab.These fields were apparently con-

structed in the following manner. Theoriginal depression soil was removed (al-though not completely in all circum-stances) and, presumably, set aside.Canals were cut into the exposed sascab.A fill mixture, composed of sascab fromthe depression and adjacent mainlandand subsoil from the depression, was laiddown between the canals (W.C.J. andJ.P.D.). This fill created a platform ele-vated about 100 cm above the sascabfloor and about 200 cm above the bot-toms of the canals. A planting mediumwas added to the platform surface, pre-sumably including the stored depressiontop soil. The result was a monolevelplatform type of raised field (8).

In some instances channelized fieldswere extended toward the depression bythe addition of a raised surface (Fig. 6).An excavation in the extension of achannelized field yielded a biface pick atthe junction of the gray fill material andthe underlying sascab, 75 cm below thesurface. Analysis indicates that the pickwas probably hafted and used as a hoe ormattock (H.J.S.). The provenience andpatterns of wear of the biface pick sug-gest that it was deposited during theconstruction of the extended segment ofthe field or of the adjacent canal. Anoth-er fragment of a biface pick was found inthe fill material of another field.The raised fields vary in shape and

size. Quadrilateral shapes are prevalent,particularly on the palmetto-dominatedfields that extend into the deeper, interi-or sections of the depression. Amor-phous shapes are common along themainland edge, where the configurationof the mainland-depression border ap-parently influenced the shape of thechannelized and adjacent raised fields.Sizes of fields range from about 80 to 750mi2, although 500 m2 is an average size.The thickness of the fill material varieswith the depth of the depression, surfacewater levels, or both, but a conservativeaverage thickness is 100 to 150 cm.A hierarchical system of canals ex-

tends through the fields. Generally, thelarger canals, from 7 to 10 m in width,link the interior of the depression withvarious segments of the fields. Largercanals commonly bifurcate and join me-dium-sized canals, about 4 m in width,which surround most of the raised fields.The depression-mainland edge is usuallyparalleled by medium-sized canals from

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which smaller canals, 2 to 3 m wide, cutinto the mainland.Whether a canal network existed in

the interior portions of the depression isnot certain. However, the discovery oftwo long canals (about 200 m long and 6to 8 m wide) that connect the southernpart of Pulltrouser South with the NewRiver indicates that a canal network didonce exist throughout the depression.Whether these long canals were used fordrainage or water-level control in thedepression or as transportation linksfrom the depression to the river is notknown. Furthermore, local accounts ofpast logging activities indicate that logswere "floated" out of the depression tothe New River. This practice probablyinvolved the use of old Maya canals, butthis interpretation is not certain.

Pollen, phytoliths, and other plant re-mains are indicators of some of the culti-vars that may have been associated withthe fields and of past environmental con-ditions. Maize (Zea mays) pollen isfound throughout the solum and fill ofthe island fields (F.J.W.). A fragment ofa carbonized maize stalk was recoveredat a depth of 35 cm in the solum at raisedfield site 2 (C.H.M.). In addition, a Gos-sypium-type pollen, perhaps cotton, andpollen of Amaranthus were found in thesoils of the raised fields. Maize, cotton,and amaranth have been suggested ascultivars grown on wetland fields by theMaya (4). Although the pollen and otherplant remains found at Pulltrouser aredirectly associated with the fields, it isnot yet certain whether they representthe remains of raised-field cultivars. Themaize pollen and fragment may havebeen deposited directly by cultivation orby the use of a mulch that containedmaize. Maize pollen in the fill materialmay also have been introduced duringthe construction of the fields. The Gos-sypium-type pollen may represent wildcotton or some malvaceous species otherthan cotton. Finally, the Amaranthuspollen may represent wild species, notthe domesticate (F.J.W.).

Paleoecological work indicates that atthe time of field use the adjacent uplandforest and the escoba-botan forest werevirtually absent and that the marsh grass-es were more dominant (F.J.W.). Phyto-liths of water lilies (Nymphaea) foundin the fields indicate the presence ofpermanent water, either at the time ofconstruction of the fields or within thecanals during field use (F.J.W.). Experi-ments on raised-field agriculture (28) in-dicate that water lilies from the canalsare a good mulch for various cropsgrown on the fields. This evidence, cou-pled with the data on molluscan species

diversity, may indicate that the canalsystem was permanently inundated.Ceramics and radiocarbon materials

provide preliminary dates of field con-struction and use. Ceramics were pres-ent in the solum and fill zones of thefields but were usually vertically mixed.Ceramic types ranged from Lopez Ma-mon (1000 to 400 B.C.) to Santana Tepeu(A.D. 600 to 850) (R.E.F.) (21). Althoughmixed materials are generally dated bythe latest ceramics, there is evidencethat the fields may have been in usebefore Santana Tepeu. A radiocarbondate of charcoal from raised field site 2,at a depth of 75 cm, was A.D. 150 ± 150(29). This date corresponds with an esti-mate based on ceramics that may datethe fields from Cocos Chicanel (400 B.C.to A.D. 250) through Nuevo Tzakol(A.D. 250 to 600) (R.E.F.). The frequen-cy of striated wares, rare until the veryLate Preclassic (Cocos Chicanel), Nue-vo Tzakol sherds found at lower levels inthe fields, and the Cocos Chicanel andNuevo Tzakol components of surfacesherds on the mainland adjacent to theraised-field sites at Pulltrouser Southwere the bases for this estimate (30). Itshould be emphasized, however, that theceramics in the fill material may havebeen redeposited during construction ofthe fields.

Settlement Study

Examination of the Maya settlementsadjacent to Pulltrouser revealed the exis-tence of at least three sites of habitation(Fig. 4) (31). Time constraints prohibiteda thorough survey of the perimeter of thedepression. Kokeal was selected for sys-tematic survey and limited excavationbecause it was the first and closest settle-ment located to the ground pattern studyat raised field site 1.Kokeal is an elongated settlement situ-

ated on a low escarpment that parallelsthe New River but changes direction toparallel the western side of PulltrouserSouth (32). Survey results revealed 117structures of different sizes that demar-cate a 1.08 km2 territory. The majority ofstructures appear to have been the plat-forms of medium-sized houses thatlacked masonry walls and vaults (33).One such structure yielded a wide rangeof artifacts-a freshwater clam cache, alithic cache, and a limestone figurine,items suggestive of ceremonial behaviorand indicative of some degree of wealth.To the south of the zone of houses aretwo small acropolises that are built ofstone and fill masonry and support atleast four pyramidal bases. There is no

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evidence that masonry walls or vaultswere used (N.E.). Furthermore, onestructure was built of earth only, piled instrata in the manner of earth mounds inNorth America.The majority of the lithics taken from

excavations at Kokeal were broken, re-touched, and recycled formal tools anddebitage from retouching and recycling(H.J.S.). Kokeal and Pulltrouser are notlocated in a chert-bearing zone; there isno evidence of the manufacture offormaltools at Kokeal; and the chert lithicsfound at Kokeal are indistinguishablefrom those produced at the major lithicworkshop site of Colha, about 26 km tothe south (Fig. 1). The majority of cherttools at Kokeal appear to have been usedin association with agricultural activities.Analysis indicates that large oval bifacepicks, including those taken from thefields, were hafted and used in a chop-ping motion against a soft but abrasivematerial, which they consistently pene-trated for about one-third of their lengthand, occasionally, for their entire length(H.J.S.). Hoeing or digging into themollisols of the mainland and field sur-faces or the underlying sascab couldhave produced the wear patterns foundon the oval bifaces (34). It is probablethat the oval bifaces were hoes or mat-tocks used to construct and cultivate thefields at Pulltrouser.

Materials from the excavations at Ko-keal included one maize cob fragmentand stem and several species often foundin dooryard orchards, such as sapodilla(Achras sapota) and copal (Protium co-pal) (C.H.M.). Evidence for cacao(Theobroma sp.) was limited to a fewwood fragments obtained by flotation offill from an earth mound. In addition,remains of Pinus caribea, a species ofpine that does not occur in the immedi-ate Pulltrouser region, were found(C.H.M.). Remains of 32 Pachychilus,an aquatic gastropod eaten by the Maya,were found at Kokeal. The species doesnot now inhabit the depression, and it isnot known whether it lives in the slow-flowing New River (A.C.).The abundance of ceramics of the Co-

cos Chicanel phase and the Santana Te-peu phase at Kokeal suggests that peakperiods of Maya activity there are asso-ciated with the Late Preclassic (300 B.C.to A.D. 150) and the Late Classic (A.D.600 to 850) (R.E.F.). Cocos Chicanelmaterial is particularly abundant in mid-den and fill contexts, and radiocarbonanalysis of charcoal remains from a mid-den produced a series of Late Preclassicdates: 35 + 55 B.C., 20 ± 50 B.C., A.D.60 ± 45 (35). However, the Preclassicmaterials have not been found in a con-24 JULY 1981

Fig. 4. Map of Puiltrouser Swamp and adja-cent settlements.

firmed constructional context (N.E.), al-though experience suggests that this cir-cumstance is related to the sample size.The earliest confirmed construction atKokeal relates to the Nuevo Tzakol ce-ramic phase, or the Early Classic (A.D.250 to 600) (N.E.). Nevertheless, theabundance of Cocos Chicanel materialsin contexts ranging from surface to con-struction fill indicates that the Kokeallocation was occupied during the LatePreclassic. The abundant Santana Tepeumaterial (Late Classic) is confirmed inconstructional context.

Interpretations and Implications

Identification. Several lines of evi-dence indicate that hydraulic agriculturewas practiced in depressions by the pre-historic Maya. The mounds of the zoneof ground patterns at Pulltrouser are notgilgai or other natural features. Gilgai donot form now and probably never didform in the depression because of chemi-cal and physical characteristics of thesoils (J.P.D. and W.C.J.). This observa-tion is corroborated by recent work atAlbion Island (16). At Pulltrouser, themorphologies of fields and canals, theprovenience of artifacts in them, and thenature of the fill material attest that thefields and canals were constructed by theMaya in the manner described above.The evidence demonstrates that at leasttwo wetland field types, channelized andraised, occur in the Maya area. Themorphology of channelized fields is simi-lar to that described at Albion Island(16), Barber Creek (17), and Cerros (36),although the composition of the bedrockvaries slightly between locations. In con-trast, raised fields (monolevel platforms)have an intervening fill between the soilsurface and the sascab.

Distribution. The evidence from Pull-trouser indicates that the fields are asso-ciated with escoba-botan forest andmarsh grasses, but not with shortgrasssavanna. Channelized fields were usedwhere inundation could be offset withoutmajor field raising, such as along theedges of depressions and higher groundadjacent to rivers; raised fields wereused where inundation was deep or pro-longed, such as within the lower parts ofdepressions.

Fig. 5. Aerial plan of raised and channelized fields and canals at raised field site 1, located alongthe midsection of the western side of the southern arm of Pulltrouser Swamp. The numberedsquares are excavation units.

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The fields and canals have been con-firmed in both riverine and depressioncontexts. These features display such aconsistent range of patterns and sizesthat their presence can be confirmed byaerial means where the patterns are dis-tinctive. The identification of well-de-fined patterns in southern Quintana Rooand other areas of Belize as relic fieldsand canals is thus supported by this work(37). Indeed, the best-preserved fields atPulitrouser are found in the bio-hydro-logical zone that is most comparable tothe bajos of southern Quintana Roo.Furthermore, the evidence complementsremote-sensing work in Belize and Petdn-that indicates the existence of 1250 to2500 km2 of terrain covered by relicfields and canals, mostly in depressions(38).Development. The evidence supports

the position that Maya agriculture in thePuiltrouser area developed first on dry-lands and subsequently included wet-lands as land pressures increased (39).Cuello, situated on the high ground be-tween the Hondo and New rivers, wasoccupied by agriculturalists as early as1950 to 1000 B.C. (21), while habitationat Kokeal and development of the Pull-trouser fields probably did not emergebefore 200 B.C. to A.D. 250. The earlyradiocarbon date (1110 ± 230 B.C.) for acanal adjacent to a wetland field at Albi-on Island suggests that riverine zonesmay have been used for wetland cultiva-tion before depression zones (11). How-ever, a caveat may be warranted in re-gard to the interpretation of that date.The ceramics taken from the fields adja-cent to the canal date no earlier than theEarly Classic (A.D. 250) (4, 40). Theincongruent dates from the two, presum-ably associated, features have not beenexplained.

Construction. It is not clear whetherthe Pulltrouser field-canal networkevolved incrementally or was imple-mented as a large project. The near-levelbed ofthe depression and the slow drain-age within it suggest that major drainageor other regulation of water levels couldnot have been accomplished in theraised-field sections without a depres-sionwide network of canals. The hierar-chy of canals and the canals linkingPulltrouser South to the New River sug-gest an overall plan for implementing thesystem. A conservative estimate of thelabor required to construct the field-canal network for the 300 ha of well-defined fields and canals is 6000 worker-years (41).

Production. The only positively identi-fied cultivar that may have been grownon the fields is maize. Cultivation of

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Chamnelized fieldsWidth Solum

(decomposeSascab limestone)

Length Solum Mott ed fill

(decomposedSascab limestone)

Raised fields SolumCanal fill Mottled filli Canal fill

Sascab (decomposed limestone)

4 mFig. 6. Plan of two types of wetland fields atPuiltrouser Swamp.

cotton is a possibility, and minimal sup-port can be given to the use of amaranth.The suggestion that cacao (Theobromasp.) was a major cultigen on the fields isunsupported (42). Estimates of field pro-ductivity are speculative for various rea-sons. The construction investment andthe evidence suggesting mulching andmucking procedures can be interpretedas indicative of high-output agriculture.Mexican chinampas are estimated tosupport about 19 people per hectare (43);a conservative figure of 4000 people canbe derived from that estimate for the 300-ha Puiltrouser network (44). It must beemphasized that many more wetlands inthe immediate area also contain raisedfields and that many of the dryland soilsare of good agricultural quality.

Settlement. Settlements immediatelysurrounding Pulltrouser were apparentlyclustered, with few structures locatedbetween clusters. If Kokeal is typical,the settlements were apparently occu-pied by farmers who cultivated the de-pression. Remains of chert tools, pre-sumably used to build and cultivate thefields, are abundant at Kokeal. Farmersmust have cultivated the mainland also;botanical evidence suggests the use ofspecies that are often found in orchardsor house gardens. A conservative esti-mate of the population of Kokeal duringthe Late Classic is 400 to 500 people (45).Kokeal may be a unique site of special

status, or it may represent a previouslyunrecognized class of such sites commonto the locality or even to the Mayalowlands in general. For example, onestructure at Kokeal is a large moundconstructed entirely of earth, whereasother building support platforms at thesite are constructed with masonry andearth fill. No platform at Kokeal sup-ported buildings with masonry walls orvaulted roofs, although these are foundat nearby San Estevan. The only paral-lels that can be found for such construc-tion shortcuts are either Olmec-datedearth structures in the Gulf Coast region

or Postclassic construction devices inthe Maya lowlands (46). In the Postclas-sic such building style has been inter-preted as a cost-control mechanism (46).Evidence of cost-control in architectureat Kokeal may also be reflected in theconsistency of recycling of chert tools.The periods of cost-control in architec-tural construction temporally flank themajor dates of occupance at Kokeal andPulltrouser at Late Preclassic and LateClassic. For this reason a unique charac-ter is postulated.

Conclusions

The Pulltrouser Swamp study has pro-vided evidence that the prehistoric Mayaused channelized and raised fields andcanals to cultivate depressions as well asriverine lands. This hydraulic technologyapparently allowed them to manipulatewater so that field soils were neitherseverely inundated nor desiccated, pro-moting conditions suitable to cultivationthroughout the year. The Pulltrouserfields were constructed no earlier thanthe Late Preclassic, apparently by farm-ers from adjacent sites such as Kokeal,and were abandoned before the Postclas-sic. This usage correlates with a recog-nized pattern of population growththroughout much of the Central Mayalowlands, including the eastern peripher-ies.The aerial patterns of the Pulltrouser

fields and wetland fields examined inriverine zones are similar to those ofnumerous wetlands throughout the east-ern and western peripheries and, per-haps, the interior of the central Mayalowlands. The similarities indicate thatwetland cultivation was widespread inprehistoric times. This interpretationsuggests that several arguments linkingthe agricultural base of the civilization tosociopolitical issues may require reeval-uation. Some of these arguments involvethe size of prehistoric populations in theregion, the relation between hydraulictypes of cultivation and levels of socialorganization, and the agricultural-envi-ronmental components that may havebeen associated with the collapse of theClassic Maya civilization.

Referces ad Notes1. B. L. Turner II, Science 185, 118 (1974).2. , in Pre-Hispanic Maya Agriculture, P.

D. Harison and B. L. Turner II, Eds. (Univ. ofNew Mexico Press, Albuquerque, 1978), pp.163-183; in Maya Archaeology and Ethnology,N. Hammond and G. R. Willey, Eds. (Univ. ofTexas Press, Austin, 1979), pp. 103-115; P. F.Healy, C. vanWaarden, T. J. Anderson, Am.Indig. 40, 773 (1980).

3. A. H. Siemens and D. E. Puleston, Am. Antiq.37, 228 (1972).

4. D. E. Puleston, in Social Process in Maya

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Prehistory, N. Hammond, Ed. (AcademicPress, New York, 1977), pp. 449-467.

5. P. D. Harrison, in ibid., pp. 469-508; C. M. St.G. Kirke, World Archaeol. 2, 181 (1980).

6. R. T. Matheny, Science 193, 639 (1976).7. P. D. Harrison and B. L. Turner II, Eds., Pre-

Hispanic Maya Agriculture (Univ. of New Mex-ico Press, Albuquerque, 1978).

8. W. M. Denevan and B. L. Turner II, J. Trop.Geogr. 39, 24 (1974).

9. G. C. Wilken, Geogr. Rev. 62, 544 (1972); E.Waddell, The Mound Builders (Univ. of Wash-ington Press, Seattle, 1972); L. M. Serpenti,Cultivators in Swamps (Royal Van Gorlum,Assen, Netherlands, 1965).

10. P. Armillas, Science 174, 653 (1971); A. Palerm,Obras hidrdulicas prehispdnicas en el sistemalacustre del valle de Mexico (Instituto Nacionalde Antropologia e Historia, Mexico D.F., 1973);T. Rojas R., R. A. Strauss K., and J. Lameiras,Nuevas noticias sobre las obras hidrdulicasprehispdnicas y coloniales en al valle de Mexico(Instituto Nacional de Antropologia e Historia,Mexico D.F., 1974).

11. A. H. Siemens, paper presented at the MemorialConference for Dennis E. Puleston, Minneapo-lis, 1979.

12. J. Belisle, S. Musa, A. Shoman, Eds., Journalof Belizean Affairs Special Issue S (1977).

13. An original estimate of the area covered byraised-field networks in a segment of southernQuintana Roo between Nicolas Bravo andUcum, 2460 kmi2, was in error M5; P. D. Harri-son, in (7), pp. 247-253]. The correct figure forthat area only is 246 km2.

14. D. E. Puleston, in (7), pp. 225-245.15. W. R. Wood and D. L. Johnson, in Advances in

Archaeological Method and Theory, M. B.Schiffer, Ed. (Academic Press, London, 1978),vol. 1, pp. 315-381; L. F. Duffield, Am. Anthro-pol. 72, 1055 (1970). W. C. Johnson (18) notesthat ground patterns could be created by bed-rock joints. Faulting could create a regular pat-tern of fractures in the underlying sascab, andthese fractures or joints could be enlarged bysolution or weathering. The result would be asurface pattern of ditches or canals. The datafrom Pulltrouser do not support this explanationof the ground patterns.

16. P. P. Antonie, R. L. Skarie, P. R. Bloom, paperpresented at the Memorial Conference for Den-nis E. Puleston, Minneapolis, 1979.

17. J. D. H. Lambert and J. T. Arnason, unpub-lished data.

18. The 1979 Pulltrouser Swamp Project, sponsoredby the University of Oklahoma and the NationalScience Foundation, included as field membersand analysts the following personnel in additionto the authors: R. E. Fry, W. C. Johnson, F. M.Wiseman, A. Covich, J. P. Darch, N. Ettlinger,A. Madeira, H. J. Shafer (from the Colha Proj-ect), C. H. Miksicek (from the Cuello Project),T. Lhurman, and C. Lincoln. In addition, floraland faunal identifications were provided by A.Gomes-Pompa, P. Cowan, and M. Pohl. Thisarticle is abstracted from the works of the per-sonnel involved. Various finds, analyses, orinterpretations of the project members are desig-nated in the text by their initials. Details of theproject are forthcoming in B. L. Turner II and P.D. Harrison, Eds., Maya Raised-Field Agricul-ture and Settlement at Pulltrouser Swamp,Northern Belize (Univ. of Texas Press, Austin,in press).

19. A. H. Siemens, in (7), pp. 100-143.20. For descriptions of depressions throughout the

area, see C. L. Lundell, Carnegie Inst. Wash.Pubi. 478 (1937); A. C. S. Wright, D. Romney,R. Arbuckle, V. Vial, Colonial Res. Publ. 24(1959), pp. 28-33; F. Miranda, in Los RecursosNaturales del Sureste y su Aprovechamiento, E.Beltran, Ed. (Instituto Mexicano de RecursosNaturales Renovables, Mexico, 1959), vol. 1,pp. 215-271.

21. N. Hammond et al., Am. Antiq. 44, 93 (1979);Nature (London) 267, 608 (1977). The chronolo-gy of the major ceramic phases follows that ofHammond and his colleagues; their radiocarbondates have been corrected to tree-ring dates.The dates reported in this article have not beencorrected in order that they may be readilycompared to the larger sets of radiocarbon datesfrom other Mesoamerican locales. Tree-ringcorrections for the periods in question are notlarge. For example, the radiocarbon date of 120B.C. is corrected to 155 B.C., a 35-year differ-ence. In most cases our chronological controlsare not sufficient to warrant consideration ofsuch short temporal distinctions.

22. Soils on the mounds have a black A horizon (forexample, Munsell color 5Y2.5/1) and a gray todark gray B horizon (for example, 5Y4/1), re-sulting primarily from decreasing organic carbonwith depth. High calcium carbonate content isdue to the calcareous parent material. Basesaturation is approximately 50 percent. Soils arepredominantly silt, but 2:1 silicate clays arepresent, imparting a high cation exchange ca-pacity. The soils correspond to the humic gleycategory of the old U.S. Department of Agricul-ture (USDA) soil classification systems (J.P.D.).

23. The solum refers to the A and B horizons only,following USDA guidelines [Agricultural Hand-book 18 (1962), p. 183].

24. Sascab (C horizon) around the perimeter of theswamp is apparently the product of deep weath-ering. Large gypsum crystals were found atdepths of about I m or more into the sascab.Initial interpretations are that the gypsum is asubstitution product associated with drier cli-matic conditions in the past (J. P. Darch, Z.Geomorphol., in press). The depth of the largegypsum crystals suggests that they formed longbefore the cultural periods discussed in thisarticle.

25. The presence of prosobranch (gill-bearing spe-cies) gastropods, such as Pyrgophorus corona-tus (Pfr.), in the excavation materials from theraised fields may indicate that the habitat oncehad permanent water I to S m deep. The habitatsof these snails are incompletely known, but thepredominance of Pomacea flagellata (Say) inthe excavations suggests that the margins of thehabitat were shallow, and the water level proba-bly fluctuated seasonally. If Pomacea shellswere used by the inhabitants for lime, the reduc-tion in the number of the species was notsufficient to prevent our recovery of the shelimaterial. Pachychilus glaphyrus (Mor.) was re-covered from excavations at Kokeal only; thesource of the species is uncertain as it is thoughtto inhabit windswept, large, deep lakes or fast-flowing rivers. If Pulltrouser was once a habitatsuitable for the species, the paucity of shellremains might be explained by harvesting of thesnail for consumption by the Maya or by therelatively low density of the species in thehabitat which precluded detection by our recov-ery procedures (A.C.).

26. E. S. Deevey, D. S. Rice, P. M. Rice, H. H.Vaughan, M. Brenner, M. S. Flannery, Science206, 298 (1979).

27. The less distinctive patterns may be vegetationlines. It is likely, however, that they representfield surfaces and canals that have been highlyeroded by the more permanent and deeper wa-ters of the interior depression. Other depres-sions in the area have distinct quadrilateralpatterns in their centers which are topped bypalmettos and are sufficiently similar to theircounterparts at Pulltrouser to be identified asraised fields. This evidence supports the interiorfield-erosion argument at Pulltrouser.

28. Various agricultural experiments on wetlandfields have been conducted at the Colegio Supe-rior de Agricultural Tropical, Cardenas, Mexi-co, under the supervision of S. Gliessman, bythe Instituto Nacional de Investigaciones sobreRecursos Bioticos, Xalapa, Mexico, under thedirection of A. Gomez-Pompa, and at Lamanai,Belize, by J. D. H. Lambert.

29. The date for this sample (Q-3117) was producedby V. R. Switsur and A. P. Ward, GodwinLaboratory, Cambridge University.

30. A temporal and spatial relation among the fieldsand canals in various segments of the depressionhas not been established. Several fields could beassigned dates by ceramic content. The fields atsite 3 (southern terminus of Pulltrouser East)appear to predate those at sites I and 2 (alongwestern edge of Pulltrouser South). However,the radiocarbon date of A.D. 150 + 150, coher-ent with the earliest ceramic materials foundmixed in several fields, comes from carbonmaterial found at site 2.

31. Mile 70, a presumed site on the northwest sideof Pulltrouser South, has not been confirmed.N. Hammond (personal communication) ob-served another site located east of the southernarm during an aerial reconnaissance. P. D. Har-rison has identified from aerial photographs alarge structure associated with this site.

32. Situated about 200 m south of the acropolises ofKokeal is a small rise on which a large platformhas been constructed to support several smallstructures. This configuration is the first ofseveral that extend south toward Orange WalkTown along the New River. These structures lay

outside the mandate of the Pulltrouser study andwere not examined in detail. Sherds collectedfrom one test pit in the platform and from theplatform surface were Late Preclassic. Thisgroup of structures has been designated as YoTumben in that it may be chronologically dis-tinct from Kokeal.

33. Because excavations were limited to test pitsand trenches, the structures have not been di-rectly confirmed as habitation structures, al-though their forms and sizes suggest that most ofthem were; the excavations produced no majorevidence to suggest otherwise. Further, the ab-sence of permanent superstructures in housemounds has been reported for the Belize RiverValley 1G. R. Willey et al., Pap. Peabody Mus.Archaeol. Ethnol. Harv. Univ. 54, 562 (1965)]. Itis possible that the absence of masonry walls inhouses might be a regional feature. The evi-dence from the San Estevan study [W. R. Bul-lard, R. Ont. Mus. Life Sci. Occas. Pap. 9(1965)] and the Corozal Project is uncertain onthis point. However, ceremonial structures didhave masonry walls and sometimes vaults.

34. Other uses and materials could have producedthe striations on the biface picks, such as cuttingvarious palms (H.J.S.). This explanation is notas consistent with the provenience and charac-teristics of the artifact as that presented.

35. The first three dates were produced at theGodwin Laboratory, Cambridge University, andthe latter two by H. Haas, Radiocarbon Labora-tory, Southern Methodist University. The 600-year error parameter for one date resulted fromthe small size of the sample that was analyzed.

36. D. Friedel and V. Scarborough, paper presentedat the Memorial Conference for Dennis E. Pu-leston, Minneapolis, 1979.

37. Recent agricultural and environmental work byS. Gliessman and B. L. Turner (in preparation)with the Colegio Superior de Agricultural Tropi-cal at Bajo Morocoy, Quintana Roo, providedconfirmation of fields and canals there. Reportsare forthcoming.

38. Various types of imagery were taken by the JetPropulsion Laboratory, Pasadena, Calif. [R. E.W. Adams, Antiquity 54, 206 (1980)].

39. W. T. Sanders, in The Classic Maya Collapse,T. P. Culbert, Ed. (Univ. of New Mexico Press,Albuquerque, 1973), pp. 325-365; B. L. TurnerII and P. D. Harrison, in (7), pp. 337-373.

40. M. Pohl, personal communication.41. This estimate is obtained from a construction

rate figure of 0.172 m3 per hour per workerderived from experimental work in Vera Cruz(A. Gomez-Pompa et al., paper presented at theMemorial Conference for Dennis Puleston, Min-neapolis, 1979) and an 8-hour workday for 365days. The estimate may be conservative in thatthe Pulltrouser fields are more elaborately con-structed features than those from which thework rates were obtained and because it isdoubtful that a 365-day work-year was used bythe Maya.

42. More than 100 soil and fill samples from thefields and structures at Kokeal were floated forplant remains and analyzed (C.H.M.). Only afew cacao fragments were found, and they weretaken from the fill of an earth mound at Kokeal.

43. W. T. Sanders, in The Valley of Mexico, E.Wolf, Ed. (Univ. of New Mexico Press, Albu-querque, 1976), pp. 101-159.

44. This estimate is based on the calculation thatabout 70 percent of the 300-ha zone was fieldsurface.

45. This estimate is based on 94 occupation struc-tures, a traditional occupancy of 5.6 persons perstructure, and use of an estimate for the noncon-temporaneity of occupation for the lower figure.

46. M. D. Coe, in The Origins ofMaya Civilization,R. E. W. Adams, Ed. (Univ. of New MexicoPress, Albuquerque, 1977), p. 190; W. J. Rathjein Ancient Civilizations and Trade, J. A. Sabloffand C. C. Lambert-Karlovsky, Eds. (Univ. ofNew Mexico Press, Albuquerque, 1975), pp.415-416.

47. We thank the Belizean Department of Archaeol-ogy, particularly E. G. Pendergast, H. Topsey,and M. Gutchin, the Royal British Air Force,the Belizean Sugar Industries, the Cuello Broth-ers, J. Bohland, the Colha Project, and variousmembers of the 1979 Cuello Project for theirassistance. Special appreciation is given to theassistance provided by N. Hammond and thecritique of the referees of this work. Most fig-ures and the typing were done by Clark Univer-sity personnel. Funding was provided by NSFgrant BSN 78-12537 and the University of Okla-homa.

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