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Download Layer Earth:Stress - Jamestown School District
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Earth Science The Dynamic Earth Introduction to Geology QuickTime™ and a Sorenson Video decompressor are needed to see this picture. The Earth Composition • There are 4 layers of the Earth – – – – Inner core Outer Core Mantle Crust The Earth’s Crust • The Earth’s crust is subjected to stress • A stress is a push or pull on the crust that causes it to change form • There are 3 main types of stress on the Earth’s crust Earth’s Structure QuickTime™ and a Sorenson Video decompressor are needed to see this picture. 3 Types of Stress • Compression - rock layers get squeezed together • Tension - rock layers get pulled apart like taffy • Shearing - rock layers get pushed in different directions causing the rock to twist and tear Two Types of Crust • There are 2 types of Earth’s crust – Oceanic - thin ( 8-10 km thick) very dense – Continental - thicker (30-70 km thick) less dense than oceanic Rock Deformation • Deformation is the term used to describe rock that has been broken, tilted, or folded • Fracture - break in rock layers • Faulting- movement of rock layers along an area of fracture • Folding - occurs when rocks are bent upward or downward Types of Folding • Anticline - rocks are bent upward (looks like an “A”) • Syncline - rocks are bent downward (looks like a “U”) Plateaus and Domes • Plateaus - a large flat area of land that is raised above sea level • Domes - an uplifted area created by rising magma (looks like a half of sphere) The Floating Crust • The Earth’s crust floats on the mantle • The mantle is made of liquid rock • Isostasy - a balance between the upward force of the mantle and the downward force of the crust
