Evidence for Continental Drift 4. CLIMATE EVIDENCE Layers of coal were found in polar regions Glacial deposits were found in tropical and temperate regions
Why was Wegener’s hypothesis rejected? 1. Wegener could not explain what was causing the continents to move.
What is theory is currently accepted? The theory of plate tectonics: Earth broken into shifting tectonic plates The plates move by a hot mantle up to a few inches a year.
Folds, Faults, & Mountains Stress is a force that can deform rocks. Three types of stress: Compression Tension Shear
Types of Stress Compression: opposing forces directed inward Tension: pulling an object in opposite directions Shear: Opposing stress is created by two plates moving in opposite directions
Types of Stress
How does stress effect rocks? Elastic: rock stretches without breaking, returns to original shape after stress is removed. Plastic: slow stretch does not return to original shape Rupture: a break in the rock.
Folds & Rock Layers Rock is layered down in nature in flat sheets A fold is a bending of rocks of the Earth’s crust. Types of folds: Anticline Syncline
Folds & Rock layers Anticline If the fold is convex upward Older rocks on inside
Folds & Rock layers Syncline If the fold is convex downward Older rocks on outside
Faults & Rock Layers IMPORTANT NEED TO KNOW!!! Occurs when large stress builds up in the crust . Types of Faults: Normal Reverse Strike-Slip
Faults & Rock Layers Normal Fault Hanging wall moved downward relative to footwall.
Faults & Rock Layers Reverse Fault Hanging wall rises relative to the footwall. Opposite of a normal fault
Faults & Rock Layers Strike-slip Fault A vertical fracture where the blocks have moved horizontally.
Folds, Faults, Mountains Overview