Tectonic and Structural Tectonic and Structural LandformsLandforms

• Both endogenicBoth endogenic• Create large-scale landformsCreate large-scale landforms• TectonicTectonic

– produced by deep Earth process without produced by deep Earth process without erosionerosion

• StructuralStructural– the result of exogenous forces acting on the result of exogenous forces acting on

tectonic landformstectonic landforms

Structural LandformsStructural Landforms

• Convergent tectonic forces produce fold Convergent tectonic forces produce fold structuresstructures– anticlines, synclines, monoclines, dome, basinsanticlines, synclines, monoclines, dome, basins

• Compressive or tensional forces produce Compressive or tensional forces produce faultingfaulting– fault scarps, horsts, grabensfault scarps, horsts, grabens

• Faults and folds impart relief to the Faults and folds impart relief to the landscape (until erosion gets to them)landscape (until erosion gets to them)

StructureStructure

• the attitude of a bed or stratum of the attitude of a bed or stratum of beds or strata of sedimentary rocks, beds or strata of sedimentary rocks, as indicated by the dip and strike.as indicated by the dip and strike.

• the disposition of the rock the disposition of the rock formations; i.e., the broad dips, folds, formations; i.e., the broad dips, folds, faults, and unconformities at depth faults, and unconformities at depth

Strike and dipStrike and dip

LithologyLithology• Relative erodibilityRelative erodibility

– Layered rocks = wide rangeLayered rocks = wide range•SedimentarySedimentary

•VolcanicVolcanic

– Massive rocks = narrow rangeMassive rocks = narrow range•MetamorphicMetamorphic

• Intrusive igneousIntrusive igneous

– Erodibility is Erodibility is notnot absolute absolute•typicallytypically shale > limestone > sandstone shale > limestone > sandstone

~ gneiss~ gneiss

LithologyLithology

http://www.uwgb.edu/dutchs/EarthSC202Notes/sedrocks.htm

Environment During Deposition

Lithology/ClimateLithology/Climate

Landforms assoc. with sedimentary Landforms assoc. with sedimentary rocksrocks

• Horizontal bedsHorizontal beds– plateau, mesa, table, butteplateau, mesa, table, butte

• Folded bedsFolded beds– anticline (arches in strata), syncline anticline (arches in strata), syncline

(trough in strata), cuesta, hogback(trough in strata), cuesta, hogback

TablelandsTablelands

• Plateau/mesa/butte/chimneyPlateau/mesa/butte/chimney

http://maunakea.com/patsadv/gallery.htm

TablelandsTablelands

Tilted Layer Tilted Layer CakesCakes

• Monoclinal foldingMonoclinal folding– beds are flexed from beds are flexed from

one level to anotherone level to another

• Feature = f(dip angle)Feature = f(dip angle)– Cuesta (gentle)Cuesta (gentle)– Hogback (steep)Hogback (steep)– Flatiron (very steep and Flatiron (very steep and

supported)supported)

• Also f(rel. erodibility)Also f(rel. erodibility)• Drainage patternsDrainage patterns

– ParallelParallel– TrellisTrellis

http://www.geog.ouc.bc.ca/physgeog/contents/10l.html

http://www.uwgb.edu/dutchs/EarthSC202Notes/sedrocks.htm

Landforms Associated with Sedimentary Rocks

Mesa Flat-topped hill capped with hard rock

Cuesta Gently-tilted layer of hard rock. The gentle upper slope, on top of the layer is called the dip slope

Hogback A sharp ridge of hard rock, edge of a steeply-dipping layer

Monocline:“A double flexure connecting strata at one level with the same strata at another level”G.K. Gilbert

RidgesRidges• Cuestas and hogbacksCuestas and hogbacks

Copyright © J. Michael Daniels 2002http://www.alperry.com/coal/grand_hogback.html

“Strike”

DipSlope

ScarpSlope

“Dip”

“Contact”

Kd

Kd

Jm

Jm

Delaware MIDelaware MIR

esistant units are typically <100’ thick and dip N

at 10-16°

1610 15

Folded Rocks – SimpleFolded Rocks – Simple http://www.geog.ouc.bc.ca/physgeog/contents/1http://www.geog.ouc.bc.ca/physgeog/contents/10l.html0l.html

• Anticline/synclineAnticline/syncline

Folded – Folded – still simplestill simple

• PlungingPlunging– Z-foldsZ-folds

Simple folds - drainage

• Contorted– Metamorphic?

• Inward/outward–Radial

–Centripetal

• Ringlike - annular

Folded Rocks - Complex

Folded Rocks - Complex

Weak

Strong

Weak Strong

“scarp slope”“dip slope”

Horseshoe Hills.kmzHorseshoe Hills

Bluntsynclinal

nose

Bluntsynclinal

nose

Sharpanticlinal

nose TOPOGRAPHY

STss