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Rocks - Coggle Diagram
Rocks
Definitions
Rocks change over a span of thousands to million of years. The continual process by which new rock forms from old rock material is called the rock cycle.
The process in which water, wind, ice, and heat break down rock is called weathering. Weathering is important because it breaks down rocks into fragments.
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Uplift is movement within the Earth that causes rocks inside the Earth to be moved to the Earth's surface. When uplifted rocks reach the Earth's surface, weathering, erosion, and deposition begin.
Types of unconformities
Disconformity
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A sequence of rock layers is uplifted. Later, younger rocks form above the erosion surface when deposition of sediment begins again.
Even though all layers are parallel, the disconformity that results shows where erosion has taken place and rock layers are missing.
Nonconformity
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Sedimentary rocks are then deposited on top of this eroded surface. The surface between the two rock types is a nonconformity.
Sometimes rock fragments from below are incorporated into sediments deposited above the nonconformity.
Angular unconformities
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Eventually younger sediment layers are deposited horizontally on top of the tilted and eroded layers.
Rock cycle
Sedimentary rocks made of sediment can also form when buried sediment is squeezed by the weight of overlying layers of sediment.
If the pressure and heat are high enough at the bottom of the sediment, the rock can change into metamorphic rock.
In some cases, the rock gets hot enough to melt. The melting creates the magma that eventually cools to form igneous rock.