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Tectonic LandformsTectonic Landforms

Landforms Landforms resulting from direct tectonic activity with little modification resulting from direct tectonic activity with little modification

by erosion (not structurally controlled landforms) Most are Holocene or by erosion (not structurally controlled landforms) Most are Holocene or

Late Quaternary in age)Late Quaternary in age)

Tectonic scarpsTectonic scarps

Fault valleys and fault block mountainsFault valleys and fault block mountains

Landforms associated with foldingLandforms associated with folding

Appalachian

Valley and Ridge

Province

How is this

landscape

formed?

Is this tectonic

geomorphology?

Tectonic scarpsTectonic scarps

ScarpScarp——any steep slope along edge of any steep slope along edge of plateau, etc. May be tectonic, erosional, plateau, etc. May be tectonic, erosional, depostional.depostional.

Tectonic scarpTectonic scarp--formed by direct tectonic formed by direct tectonic actionaction

–– Normal fault scarpNormal fault scarp

–– Thrust fault scarpThrust fault scarp

–– Fault line scarpFault line scarp

–– Strike slip fault landformsStrike slip fault landforms

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Normal fault scarpsNormal fault scarps Preserves original fault angle only when Preserves original fault angle only when

very recent. Erosion reduces angle very very recent. Erosion reduces angle very

quickly, especially in unconsolidated quickly, especially in unconsolidated

materials. materials.

East slope;

Colorado

Rockies D

U

Mountain front sinuosityMountain front sinuosity

J = LJ/LS : index of fault

activity. The higher the

value, the less active the

fault.

A-B: initial activity; C-D: maximum relief;

E: tectonic quiescence, dominance of

fluvial activity.

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Death Valley

Sonoma Range, Nevada

Normal Fault landformsNormal Fault landforms

Sierra Nevadas Ground View of fault

Sierra Nevadas Red Canyon fault-Hebgen Earthquake

1959

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Hebgen Scarp

2002, Denali fault, Alaska

Triangular facetsTriangular facets

Produced by stream

erosion of fault scarp

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Bottleneck canyon, Death Valley

Thrust faults don’t always Thrust faults don’t always

produce wellproduce well--defined scarpsdefined scarps

Section at left being thrust over lighter sandstone at right

Keystone thrust, Nevada

Termination of a fault scarpTermination of a fault scarp

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FaultFault--line scarpsline scarps

No fault movement in present erosion

cycle.

(a) Continuity of lava flow shows that

scarp is erosion rather than fault

related.

(b) Scarp faces toward uplifted

side.

Landforms produce by strikeLandforms produce by strike--slip faultingslip faulting

Shutter ridgesShutter ridges

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Garlock fault-left lateral Carrizo Plain-San Andreas

San Andreas

Offset drainagesOffset drainages

San Andreas San Jacinto fault

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Sag PondsSag Ponds

Alaska

San Andreas

Fault valleys and faultFault valleys and fault--block mountainsblock mountains

HorstHorst

GrabenGraben

TypesTypes

–– OregonOregon——flat lying rocksflat lying rocks

–– Basin and RangeBasin and Range——tilted, deformed rocks, grabens tilted, deformed rocks, grabens

and half grabens in arid climateand half grabens in arid climate——basins are alluvial basins are alluvial

desert basinsdesert basins——no throughno through-- flowing streamsflowing streams

–– New ZealandNew Zealand——humid equivalenthumid equivalent——through flowing through flowing

streams at bases of scarpsstreams at bases of scarps

Oregon typeOregon type--IcelandIceland

Reykanes Peninsula Thingvellir

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Basin and Range StructureBasin and Range Structure

Fault-block mountains-Nevada

GrabensGrabens

Garlock Fault, CA Panamint Range, CA

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Rift ValleysRift Valleys

Red

Sea

Dead

Sea

rift

Folding and LandformsFolding and Landforms

MonoclinesMonoclines

Topographic domesTopographic domes

–– Salt TectonicsSalt Tectonics

Salt domes; Gulf CoastSalt domes; Gulf Coast

Salt anticlines; Colorado PlateauSalt anticlines; Colorado Plateau

–– Igneous DomesIgneous Domes

Waterpocket Monocline, UtahWaterpocket Monocline, Utah

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East Kaibab monocline, Arizona

Uplift of geomorphic surfacesUplift of geomorphic surfaces

Shows relationship between geomorphology

and active tectonics.

AlaskaAlaska

11 ft. uplift during 1964 earthquake

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Moab anticlineMoab anticline

ASTER image of salt dome, Iran

Igneous domesIgneous domes

Laccoliths, Texas