BASIC GEOLOGY BASIC GEOLOGY CONCEPTSCONCEPTS

Luanne VanderpoolLuanne VanderpoolU. S. EPA Region 5 U. S. EPA Region 5 Tech SupportTech Support

NARPMNARPMBaltimore, May 23, 2007Baltimore, May 23, 2007

Introduction to Contaminant Hydrogeology:

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GeologyGeology

The study of the origin, history, composition, The study of the origin, history, composition, and structure of the earth. and structure of the earth.

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Basic Geology ConceptsBasic Geology Concepts

LithologyLithology: Study of Earth Materials: Study of Earth Materials Rocks and SoilRocks and Soil33--Dimensional Distribution of Earth Dimensional Distribution of Earth MaterialsMaterials StratigraphyStratigraphy StructureStructureGeology of Ground Water OccurrenceGeology of Ground Water OccurrenceMaps and Cross SectionsMaps and Cross Sections How we portray the materialsHow we portray the materials

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Earth MaterialsEarth Materials

Unconsolidated materialsUnconsolidated materials SoilSoil SedimentSediment DirtDirt RegolithRegolithConsolidated materialsConsolidated materials Rocks: Particles of various sizes and shapes Rocks: Particles of various sizes and shapes

welded together by heat, pressure or welded together by heat, pressure or chemical reactions into a solid masschemical reactions into a solid mass

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Consolidated Rock TypesConsolidated Rock Types

Igneous RocksIgneous Rocks

Sedimentary RocksSedimentary Rocks

Metamorphic RocksMetamorphic Rocks

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Rock TypesRock TypesIgneous RocksIgneous Rocks

Formed by cooling and crystallization of Formed by cooling and crystallization of lava and magma (melted matter)lava and magma (melted matter)Examples Examples Basalt, Granite, Basalt, Granite, GabbroGabbro

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BasaltBasalt

88

BasaltBasalt

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GraniteGranite

1010

Rock TypesRock Types

Sedimentary Rocks Sedimentary Rocks

Formed by the consolidation of loose Formed by the consolidation of loose particles (mud, sand, boulders, shell and particles (mud, sand, boulders, shell and coral fragments) coral fragments) Conglomerate, Sandstone, Siltstone, ShaleConglomerate, Sandstone, Siltstone, ShaleFormed by precipitation from solutionFormed by precipitation from solution Limestone, Dolomite, Limestone, Dolomite, EvaporitesEvaporitesComposed of parts of living thingsComposed of parts of living things Limestone, CoalLimestone, Coal

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ConglomerateConglomerate

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Conglomerate Conglomerate and and

SandstoneSandstone

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Close-up View of Sandstone

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ShaleShale

5 cm

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Rock TypesRock Types

Metamorphic Rocks Metamorphic Rocks

Formed by heat and pressure changing Formed by heat and pressure changing the original (parent) rock into a completely the original (parent) rock into a completely new rocknew rock Slate, Schist, GneissSlate, Schist, Gneiss Quartzite, MarbleQuartzite, Marble

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SlateSlate5 cm

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SchistSchist

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Outcrop of GneissOutcrop of Gneiss

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QuartziteQuartzite

2020

MarbleMarble

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The Rock CycleThe Rock Cycle

The rock cycle The rock cycle portrays the portrays the interrelationships interrelationships among the three among the three rock groups. rock groups.

IGNEOUSROCKS

METAMORPHICROCKS

SEDIMENTARY

ROCKS

melt

ing melting

temperature

& pressure

temperature& pressure

erosion &deposition

eros

ion &

depo

sition

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Questions to AskQuestions to Ask

What is the Regional Ground Water What is the Regional Ground Water Setting?Setting?Is the geology of the site typical for the Is the geology of the site typical for the area?area?Are there local features (fractures, sand Are there local features (fractures, sand lenses) at the site that may control flow? lenses) at the site that may control flow? What, Where, How deep?What, Where, How deep?Do I have one or more geologic cross Do I have one or more geologic cross sections for the site?sections for the site?

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WeatheringWeathering

The weathering The weathering process fractures and process fractures and dissolves rock and dissolves rock and creates soilcreates soil

Two types of Two types of weatheringweathering PhysicalPhysical ChemicalChemical

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WeatheringWeathering

Granite in various Granite in various stages of weatheringstages of weathering

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What is Soil?What is Soil?

To an Agronomist: the weathered upper To an Agronomist: the weathered upper layers of earth material capable of layers of earth material capable of supporting plant lifesupporting plant lifeGeologist: the weathered upper layers of Geologist: the weathered upper layers of earth material covering rocksearth material covering rocksHydrologist/Engineer: surficial material Hydrologist/Engineer: surficial material that will disaggregate (fall apart) when that will disaggregate (fall apart) when subjected to gentle mechanical force.subjected to gentle mechanical force.

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Basic Soil ConceptsBasic Soil Concepts

Grain SizeGrain SizeSorting and GradingSorting and GradingPorosityPorosity

These terms are also used to describeThese terms are also used to describerocks.rocks.

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Grain SizeGrain Size

Grain sizeGrain size refers to the physical dimensions of refers to the physical dimensions of particles of sedimentary rock or soil.particles of sedimentary rock or soil.

Gravel: Gravel: > > 2 mm2 mm ConglomerateConglomerateSand: Sand: 1/16 1/16 -- 2 mm2 mm SandstoneSandstoneSilt: Silt: 1/256 1/256 -- 1/16 mm1/16 mm SiltstoneSiltstoneClay: Clay: < < 1/256 mm1/256 mm Shale/MudstoneShale/Mudstone

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Grain Size ExamplesGrain Size Examples

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Sorting and GradingSorting and GradingSoils of mixed grain size may be Soils of mixed grain size may be described by their sorting or described by their sorting or grading. grading. A well sorted soil has particles of A well sorted soil has particles of similar size similar size A poorly sorted soil has particles A poorly sorted soil has particles with a variety of sizeswith a variety of sizes

But to an engineer But to an engineer A poorly sorted soil is well graded A poorly sorted soil is well graded A well sorted soil is poorly graded A well sorted soil is poorly graded

POORLY-GRADED SANDWELL-SORTED SAND

WELL-GRADED SANDPOORLY-SORTED SAND

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PorosityPorosity

Soil and rock contains voids: spaces, Soil and rock contains voids: spaces, cracks, porescracks, poresThe voids are filled with fluid (air, water)The voids are filled with fluid (air, water)Porosity measures the amount of voidsPorosity measures the amount of voids

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PorosityPorosity

PrimaryPrimary

SecondarySecondary Fractures in GraniteFractures in Granite Caverns in LimestoneCaverns in Limestone

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Knowledge of Knowledge of lithologylithology, stratigraphy and structures , stratigraphy and structures leads to understanding of distribution of aquifers leads to understanding of distribution of aquifers and confining units.and confining units.

LithologyLithology Physical make up of Physical make up of

soil and rockssoil and rocks

StratigraphyStratigraphy Geometric and age Geometric and age

relationshipsrelationships

StructureStructure Features produced by Features produced by

deformationsdeformations

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WaterWater--Bearing Rocks Bearing Rocks

Sands and GravelsSands and GravelsSandstoneSandstoneLimestone and Limestone and dolomitedolomiteBasaltBasaltOtherOther

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StratigraphyStratigraphy

Sedimentary rock Sedimentary rock (and layered igneous (and layered igneous rocks) have rocks) have stratification or stratification or bedding.bedding.Contacts between Contacts between layers or strata are layers or strata are called bedding planescalled bedding planesGround water may Ground water may move more easily move more easily along bedding planesalong bedding planes

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Basic Structure ConceptsBasic Structure Concepts

Structural Geology is the study of the Structural Geology is the study of the 33--dimensional distribution of rock dimensional distribution of rock bodies and the processes which bodies and the processes which deform (fold, break) them.deform (fold, break) them.

FoldsFoldsFracturesFracturesFaultsFaultsJointsJoints

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FoldsFolds

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FoldsFolds

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Fractures Fractures -- FaultsFaultsFaults are fractures along which there has been Faults are fractures along which there has been displacement of the material on either side of the displacement of the material on either side of the fault.fault.

Fractures and Fractures and faults can be faults can be a significant a significant pathway for pathway for ground water ground water flow.flow.

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Fractures: JointsFractures: JointsJoints are fractures along which there has been no Joints are fractures along which there has been no displacement.displacement.

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Ground Water RegionsGround Water Regions

Alaska

1

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Ground Water RegionsGround Water Regions1. Western Mountain 1. Western Mountain

RangesRanges2. Alluvial Basins 2. Alluvial Basins 3. Columbia Lava Plateau:3. Columbia Lava Plateau:4. Colorado Plateau and 4. Colorado Plateau and

Wyoming BasinWyoming Basin5. High Plains5. High Plains6. 6. NonglaciatedNonglaciated Central Central

RegionRegion7. Glaciated Central Region7. Glaciated Central Region8. Piedmont and Blue Ridge8. Piedmont and Blue Ridge

9. Northeast and Superior 9. Northeast and Superior UplandsUplands

10. Atlantic and Gulf 10. Atlantic and Gulf Coastal PlainCoastal Plain

11. Southeast Coastal Plain11. Southeast Coastal Plain12. Alluvial Valleys12. Alluvial Valleys13. Hawaiian Islands13. Hawaiian Islands14. Alaska14. Alaska15. Puerto Rico and Virgin 15. Puerto Rico and Virgin

IslandsIslands2

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Maps and Cross SectionsMaps and Cross Sections

Contour mapsContour maps

Geologic mapsGeologic maps

Cross sectionsCross sections

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Contour MapsContour Maps

Topographic maps Topographic maps show variations in show variations in the elevation of a the elevation of a land surface.land surface.

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Topographic MapTopographic Map

Tightly spaced contour Tightly spaced contour lines describe steep lines describe steep changes in elevation, changes in elevation, Areas of very few Areas of very few contours portray flat contours portray flat areasareas

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Geologic MapGeologic Map

A geologic map is a A geologic map is a special map that special map that shows the distribution shows the distribution of different kinds of of different kinds of rocks or sediments rocks or sediments and structural and structural features (e.g. faults). features (e.g. faults).

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Geologic MapsGeologic MapsA geologic map A geologic map has a legend that has a legend that identifies rock identifies rock types and relative types and relative ages of rock units.ages of rock units.

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Cross SectionsCross Sections

A cross section or A cross section or profile is a vertical profile is a vertical slicesliceA topographic profile A topographic profile is a slice through a is a slice through a topographic map. topographic map.

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Geologic Cross SectionsGeologic Cross Sections

A geologic cross section is a vertical view of A geologic cross section is a vertical view of strata.strata.

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Geologic Cross SectionsGeologic Cross Sections

By interpreting the sequence of events which By interpreting the sequence of events which produced the strata it is possible to gain produced the strata it is possible to gain insight into the geologic history of a region.insight into the geologic history of a region.

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Least You Need to KnowLeast You Need to KnowGeology (Geology (lithologylithology, stratigraphy, structure) , stratigraphy, structure) forms the framework for where ground forms the framework for where ground water is found.water is found. thus controlling where groundwater thus controlling where groundwater

contamination is found. contamination is found. Effective site investigations consider and Effective site investigations consider and use site geology to select groundwater use site geology to select groundwater sampling locations.sampling locations.Understanding of site geology impacts Understanding of site geology impacts remediation cost and effectiveness remediation cost and effectiveness

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Questions to AskQuestions to Ask

What is the regional ground water setting?What is the regional ground water setting?Is the geology of the site typical for the Is the geology of the site typical for the area?area?Are there local features (fractures, sand Are there local features (fractures, sand lenses, clay units) at the site that may lenses, clay units) at the site that may control flow? control flow? What, Where, How deep?What, Where, How deep?Do I have one or more geologic cross Do I have one or more geologic cross sections for the site?sections for the site?

Basic Geologic Concepts Basic Geologic Concepts Case StudyCase Study

ThermalkemThermalkem SiteSite

ThermalkemSite Location

North Carolina

South

Carol

ina

Site

Thermalkem Site

Geologic Map of Thermalkem Site

Gabbro Mica Gneiss

ThermalKEMFacility

Rock Hill , SC

ThermalKEMRock Hill, SC

KEY

Approximate Locationsof Bedrock Lineaments

Fracture Trace Map

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LOG OFGROUNDWATER

MONITORING WELLMW-102

GROUND SURFACEELEVATION 529.0

4.0

9.0

13.0

10.0

19.0

22.0

34.0 '34.0

24.0

23.3

ThermalKEMRock Hill, SC

Silty Clay

Silt and Fine SandFrac. RockSandy Clay

SiltySand

Sandy Clay

Bedrock

Gabbro

Cement Grout

Open Hole

ThermalKEMRock Hill, SC

F'F'

F

Cross-Section Location Map

Monitoring Well

Along F-F

Site

GEOLOGIC CROSS-SECTION LINE F- F'ThermalKEM Facility, Rock Hill , SC

540

520

500

480

460

440

540

520

500

480

460

440

I

SA SA SA

OB OB OB

SA SA

BR

SA

SA

OB OBOB

BR

SA

FEET

0 30 60

PW2A

Geologic Cross-Section, F-F, Thermalkem

MW-115BMW-114 MW-113B

F

Bedrock

Saprolite

OB-12

Screened (intake) interval

FSite