Tectonic and Structural Landforms Both endogenic Create large-scale landforms Tectonic produced by deep Earth process without erosion Structural the result of exogenous forces acting on tectonic landforms endogenic: produced by interior Earth forces. exogenous: weathering, gravity, water, glaciers, waves, wind

Everest is (largely) a tectonic landform, Lone Mt is a structural landform: Christmas tree laccolith, with weaker country rock eroded away. Equifinality.

Structural Landforms Convergent tectonic forces produce fold structures anticlines, synclines, monoclines, dome, basins Compressive or tensional forces produce faulting fault scarps, horsts, grabens Faults and folds impart relief to the landscape (until erosion gets to them)

Structure the attitude of a bed or stratum of beds or strata of sedimentary rocks, as indicated by the dip and strike. the disposition of the rock formations; i.e., the broad dips, folds, faults, and unconformities at depth

Strike and dip strike and dip are perpendicular. strike is the line of intersection of a horizontal plane with the geologic plane.

Lithology Relative erodibility Layered rocks = wide range Sedimentary Volcanic Massive rocks = narrow range Metamorphic Intrusive igneous Erodibility is not absolute typically shale > limestone > sandstone ~ gneiss

Lithology http://www.uwgb.edu/dutchs/EarthSC202Notes/sedrocks.htm Environment During Deposition                                                                                                                                                                                                                        http://www.uwgb.edu/dutchs/EarthSC202Notes/sedrocks.htm

Lithology/Climate

Landforms assoc. with sedimentary rocks Horizontal beds plateau, mesa, table, butte Folded beds anticline (arches in strata), syncline (trough in strata), cuesta, hogback

Tablelands Plateau/mesa/butte/chimney http://maunakea.com/patsadv/gallery.htm

Tablelands

Tilted Layer Cakes Monoclinal folding Feature = f(dip angle) beds are flexed from one level to another Feature = f(dip angle) Cuesta (gentle) Hogback (steep) Flatiron (very steep and supported) Also f(rel. erodibility) Drainage patterns Parallel Trellis http://www.geog.ouc.bc.ca/physgeog/contents/10l.html

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

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

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

Kd Jm “Contact” “Dip” “Strike” Dip Slope Scarp Slope

Delaware MI 10 15 16 Resistant units are typically <100’ thick and dip N at 10-16°

Folded Rocks – Simple http://www. geog. ouc. bc Anticline/syncline

Folded – still simple Plunging Z-folds

Simple folds - drainage Contorted Metamorphic? Inward/outward Radial Centripetal Ringlike - annular

Folded Rocks - Complex

Folded Rocks - Complex Horseshoe Hills Strong Weak “dip slope” Strong “scarp slope” Horseshoe Hills

Tuscarora sandstone Tuscarora sandstone

Tuscarora sandstone Tuscarora sandstone Blunt synclinal nose STss Sharp anticlinal nose TOPOGRAPHY