Effects of Plate Tectonics Part I Forces Shape the Land
Definition: Isostasy When plates move, they balance to equilibrium on athenosphere Example: Drop block in water, and it bobs up & down, then floats
Major Forces Stress/Strain: Compression, Shearing, Tension Folding/Deformation: Anticline, Syncline, Monoclines (Rocks don’t break) Faulting: Normal, Reverse, Strike-Slip (Rocks do break) These forces can create: 1) Landform changes 2) Mountains 3) Earthquakes 4) Volcanoes
types of folds Anticline – “A” Shaped
types of folds Syncline – remember “smile” shaped
types of folds Monocline – slightly curved
Folds Animation Link http://ees.as.uky.edu/sites/default/files/elearning/module10swf.swf http://www.wwnorton.com/college/geo/earth3/content/ch11/animations.asp
fault terminology Fault – fracture in rock along which there has been displacement Hanging wall – rock surface above the fault Footwall – rock surface below the fault Fault scarp – exposed fault surface
Caused by tension forces Hanging wall moves down Normal Faults Caused by tension forces Hanging wall moves down
Reverse Faults Caused by compression forces Hanging wall moves up
Opposing forces cause rock to break Strike-slip Faults Opposing forces cause rock to break Move horizontally
Animation Link: http://www.classzone.com/books/earth_science/terc/content/visualizations/es1103/es1103page01.cfm http://www.iris.edu/gifs/animations/faults.htm
Questions for Review What is isostasy? Explain the difference among compression, shearing, and tension. What is the difference between a fold and a fault? Name the 3 types of folds and their shape. What are the 3 types of faults? What are some effects of plate tectonics?
CE Questions As a volcanic mountain range is built, isostatic adjustment will cause the crust beneath it to: A) Break B) Sink C) Rise D) Fold
CE Questions As a volcanic mountain range is built, isostatic adjustment will cause the crust beneath it to: A) Break B) Sink C) Rise D) Fold
CE Questions Isostatic adjustments continue until the forces pressing the crust up and down are: A) Balanced B) Doubled C) Decreased D) Removed
CE Questions Isostatic adjustments continue until the forces pressing the crust up and down are: A) Balanced B) Doubled C) Decreased D) Removed
CE Questions Folding of rocks is most likely to happen when rocks undergo: Tension Shearing Compression Cooling
CE Questions Folding of rocks is most likely to happen when rocks undergo: Tension Shearing Compression Cooling
CE Questions Rocks deeper in the earth’s crust are less likely to deform by breaking than rocks closer to the earth’s surface because of: A) Lower stresses B) Higher temperature C) Higher strains D) Lower altitude
CE Questions Rocks deeper in the earth’s crust are less likely to deform by breaking than rocks closer to the earth’s surface because of: A) Lower stresses B) Higher temperature C) Higher strains D) Lower altitude
CE Questions Which causes reverse faults? A) Compression B) Shearing C) Tension D) Folding
CE Questions Which causes reverse faults? A) Compression B) Shearing C) Tension D) Folding
CE Questions Where do strike-slip faults often occur? A) At mid-ocean ridges B) In the lower half of the crust C) Between ridges D) Along transform plate boundaries
CE Questions Where do strike-slip faults often occur? A) At mid-ocean ridges B) In the lower half of the crust C) Between ridges D) Along transform plate boundaries
CE Questions Explain the cause and effect of normal, reverse, and strike-slip faults (be specific).
CE Questions What is the result of a….convergent boundary….divergent boundary…transform…? Which produces new crust? Which takes place on continental crust? Which takes place in the ocean? Which boundary is located in California?
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