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Chapter 15.4 Deforming the Earth’s Crust stress • a force that acts on rock deforming it’s shape or volume 3 types of stress shearing tension compression pushes rock in opposite directions pulls on crust stretches rock so that it becomes thinner in the middle squeezes rock until it folds or breaks YouTube video-Bill Nye Stress Stress causes rocks to either fold (bend) or fault (break). Folding • fold-bend in rock that forms when compression shortens & thickens part of Earth’s crust – can create folded Mountains Folded Mountains Three Types of Folds • Anticline • Syncline • Monocline Anticline •fold in rock layers that forms an Arch Syncline • fold in rock layers that bends down to form a bowl – SMILEY FACE! Anticline & syncline Anticline & syncline Monocline • Rock layers are folded so that both ends of the fold are horizontal. 3 types of faults strike-slip normal reverse caused by shearing caused by tension caused by compression Hanging Wall/Footwall Normal fault hanging wall moves down relative to the footwall footwall hanging wall Normal Faults Reverse fault hanging wall moves up relative to the footwall footwall hanging wall Reverse Fault Strike-Slip Fault • Faulting at a transform boundary – fault blocks slide past each other What kind of fault is this? strike-slip fault Example of a strike-slip fault San Andreas fault Fault-Block Mountains • mountains formed when normal faults cause large blocks of rocks to slip down due to tension Grand Teton mountain range fault-block mountain Uplift and Subsidence • Vertical movements in the crust are divided into two types— – Uplift – the rising of regions of the Earth’s crust to higher elevations (mountains and rebound – slow movement back to normal level after weight is removed) – Subsidence – sinking of regions of Earth’s crust to lower elevations (rift zones and oceanic crust as it moves away from the ridge) plateau= large area of flat land elevated high above sea level (an area of uplift) • The Colorado Plateau is a 150,000 square mile region covering parts of Arizona, Utah, Colorado, and New Mexico. syncline • What is a fold in rock layers that bends down to form a bowl ? syncline syncline fold What is a bend in rock that forms when compression shortens & thickens part of Earth’s crust ? A fold is a bend in rock that forms when compression shortens & thickens part of Earth’s crust. A fold is a bend in rock that forms when compression shortens & thickens part of Earth’s crust. fault-block mountain • What is a mountain formed when normal faults cause a block of rock to slip down? Sierra-Nevada mountain range anticline • What is a fold in rock layers that forms an arch ? • In a _____________ fault, the rocks on either side of the fault slip past each other sideways. • In a strike-slip fault, the rocks on either side of the fault slip past each other sideways. What are the 3 types of stress ? shearing tension compression • The 3 types of stress are shearing, tension and compression. • The 3 types of stress are shearing, compression. tension and tension What type of stress pulls on the crust, stretching the rock so that it becomes thinner in the middle ? • What type of stress pushes rock in opposite directions? A. tension B. shearing What are the 3 types of faults? 1. strike-slip 2. normal 3. reverse What type of fault is caused by shearing? A. B. C. D. Strike-slip Normal Reverse Fault-block