The Rock Cycle Chapters 5 & 6

What are the types of rock? Igneous rocks Form from cooling magma Recall: magma is molten material beneath Earth’s surface Sedimentary rocks Form from cementing and compacting pieces of sediment Sediment is pieces of solid material deposited on Earth’s surface Metamorphic rocks Rocks that have been changed from heat and pressure

Igneous Rocks Formation of igneous rock Intrusive Formed by magma that cools slowly Formed beneath the Earth’s surface Coarse-grained Ex. granite Extrusive Formed by magma that cools quickly Formed above the Earth’s surface Fine-grained Ex. Rhyolite

Properties of igneous rock Mineral composition Light colored = felsic Dark colored = mafic Grain size Coarse-grained = intrusive Fine-grained = extrusive

Sedimentary Rocks Formation of sedimentary rock Weathering produces sediments Physical weathering Happens when rock fragments break off. Ex. Temperature changes expand or contract rock Living organisms like trees crack rocks

Chemical weathering Happens when the minerals in rocks are chemically changed Ex. Dissolving Oxidation (rust)

Erosion transports weathered sediments from one place to another Types of erosion Wind Moving water Gravity Glaciers

Deposition is when sediments are laid down on the ground or under water This can cause sorting of sediments into layers, which is called bedding. Deposited sediments become buried

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Lithification happens when the weight of overlaying sediments forces grains closer together. Water is pressed out Sand is compacted High temperatures (~3-4km deep) cause cementation New minerals can grow between cemented sediments

Properties of sedimentary rock Clastic—formed from deposits of loose sediments rth_science/terc/content/visualizati ons/es0605/es0605page01.cfm?c hapter_no=visualization Chemical—formed from precipitation of minerals dissolved in water Organic—formed from accumulation and lithification of dead organisms Ex. coal

Metamorphic Rocks Formation of metamorphic rocks High temperatures and pressures increase with depth High temperature comes from Earth’s internal heat or intruding magma. High pressure comes from overlying rock or the compression of mountain building Rocks do not melt, but change in texture, mineralogy, or chemical composition rth_science/terc/content/visualizati ons/es0607/es0607page01.cfm?c hapter_no=visualization

Properties of metamorphic rocks Texture Foliated—wavy layers and bands of minerals Nonfoliated—minerals form blocky crystals Mineral composition Heat & pressure can change one mineral into another Chemical composition Hot fluids go in and out of the rock during metamorphism, changing its chemistry

What is the rock cycle? The rock cycle is the continuous changing and remaking of rocks Any type of rock can turn into any other type of rock Matter making up rocks is neither crated nor destroyed, but simply changed.

Processes that power the rock cycle Internal processes Uplift Heat & pressure Melting Cooling & crystallization External processes Uplift Weathering & erosion Deposition, burial, & lithification