Rock Cycle
A model that describes the formation, breakdown, and reformation of a rock. Sedimentary Rock •Formed when sediments accumulate and compact and cement together. •Often deposited in layers and contain sand, pebbles, and frequently fossils. Ex. sandstone, limestone Physical properties of Sedimentary Rocks •Sand, pebble, and even boulder size particles •Some may contain fossils By what process are sedimentary rocks broken down? Weathering •By weather (rain, ice, wind), chemical changes, and living things (plant). •Creates lose material called sediments. By what process are sediments moved? Erosion •Wind •Water •Gravity •Ice They are deposited in layers - Deposition What are the processes that form sedimentary rock? Compaction Sediments are deeply buried, placing them under pressure because of the weight of overlying layers. Cementation •New minerals stick the sediment together just like cement. •This holds the grains together tightly. Metamorphic Rock •Formed by heat and pressure while buried deep below Earth’s surface. •Have a layered or banded (ribbon like) appearance or may have crystals. Ex. Gneiss, Marble, Slate Physical Properties of Metamorphic Rocks •Layers look like ribbons •Crystals What are the processes that form metamorphic rock? Heat (caused by magma) •Temperatures high enough to change its structure but not to melt it. •Heat can change sedimentary, igneous, or another older metamorphic rock. Pressure - Caused by intense collisions and friction of tectonic plates and pressure from overlying rock layers. •Deep under the Earth’s surface. •Pressure can change sedimentary, igneous or another older metamorphic rock. Igneous Rock •Formed when lava or magma harden. •Found near volcanoes or fissures •Ex. Basalt, Obsidian, Granite Physical Properties of Igneous rock Fast Cooling Slow Cooling Glassy Large crystals Holes where gas was trapped Many colors What are the processes that form Igneous rock? Melting •Caused by increase in temperature in rock deep below the surface of Earth •Caused by friction between crustal plates Lava –molten rock material on Earth’s surface. Magma – molten rock material under Earth’s surface. What are the processes that form igneous rock? Cooling and Hardening •Melted rock turns solid. •Slow cooling happens below Earth’s surface as magma cools forming large crystals. Ex. granite •Fast cooling happens on the Earth’s surface as lava cools forming small crystals. Ex. obsidian, basalt, pumice Comments are closed.
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Erik E. Mason
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