I Evidence For Dynamic Earth a km3 of crustal rock skyward b Erosion grinds c Mountains occur in linear ranges i Mountain belts ii Orogenic belts iii Orogens d Approximately 1 dozen mountain belts II Why Mountains Form a Plate tectonics i Motion on transform faults ii Subducting iii Rifting iv Continental Collision b Deformation i Rock is squeezed stretched or sheared ii Yields geologic structures 1 Joints a Cracks due to tension b Brittle rock i Cools and contracts Layers at depth experience pressure decrease erosion c d Rock layers bend 2 Faults a Fracture where slip occurs b Hanging wall vs foot wall i Dip slip reverse or normal ii Strike slip right left lateral c Thrust faults shorten and thicken crust d Normal faults lengthen and thin crust 3 Folds a Due to ductile deformation b Parts of fold c Types i Axial plane ii Limbs iii Hinge i Anticline ii Syncline iii Monocline 4 Foliation a Tectonic foliation layering created by the alignment of deformed and or reoriented grains c Strain i Change in shape ii Types of strain 1 Stretching 2 Shortening i Buoyancy force pushing lithosphere up gravitational force pulling lithosphere down ii Surface elevation of crust 1 Reflects level lithosphere naturally floats 1 Brittle deformation joints faults 2 Ductile deformation folds foliation 3 Shear iii Permanent strain iv Factors 1 Temperature 2 Pressure 3 Rate 4 Composition III Uplift a Forms mountain topography b c Mt Everest Large vertical displacement surface of crust i 8 85 km above sea level d Isostacy IV Sculpting Mountains by Erosion a Over time ice and water sculpt uplifted land b Erosion factors i Climate 1 High elevations glaciers 2 Low elevations rivers ii Soil development iii Bedrock composition iv Geometry 1 Cuesta 2 Hogback c Mountains can t be too high i Erosion ii Rock strength 1 Warms and flows at depths 2 Mountains collapse under own weight d Exhumation i Erosion and orogenic collapse V Causes of Mountain Building a Convergence i Accreted terranes ii Exotic terranes iii Fold thrust belt i Fold thrust belt ii Crustal thickening b Collision c Rifting i Uplift ii Normal faulting d Cratons i Crust unaffected by orogeny for at least 1 Ga ii Strong and stable areas iii Two provinces 1 Shields precambrian rock 2 Cratonic platform