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Today we’ll investigate… The rock cycle Minerals Next Week… Rock cycle Lab TEST!

The Rock Cycle

rock cycle – rock is created, changes from one form to another, is destroyed, and forms again by geological processes The three types of rock can be changed into any of the three types by geologic forces and processes

Three Major types of Rocks Sedimentary Metamorphic Igneous

Igneous Rocks Rock that forms when magma cools and solidifies Three factors that affect whether rock melts include temperature pressure the presence of fluids in the rock

Types of igneous rocks Basalt Granite Pumice Obsidian

Fractional Crystallization Chemicals in magma combine to form minerals Fractional Crystallization- crystallization and removal of different minerals from the cooling magma Each mineral has a different freezing point. Minerals that have the highest freezing points crystallize first

Textures of Igneous Rock Intrusive-magma cools inside of earth Crystals tend to be large Course grained Example is granite Extrusive-magma cools outside of earth Crystals tend to be small Fine grained

More on texture Glassy-cools rapidly without dissolved gas Obsidian Vesicular-cools rapidly with a lot of dissolved gas Pumice Porphyritic-cools slowly than rapidly Has large crystals imbedded in smaller ones

Sedimentary Rocks Rock is made up of combinations of different types of sediment loose fragments of rock, minerals, and organic materials. Compaction -the volume and porosity of sediment is decreased by the weight of overlying sediments cementation - minerals move into holes between sediment grains and bind sediments together to form rock

Types of Sedimentary Rock Coal Limestone Shale Sandstone

3 Types Chemical -forms from minerals once dissolved in water Evaporation leaves behind minerals that form rocks Gypsum and halite Organic -forms from the remains of living things Compacted and cemented together Coal and limestone Clastic -form from rock fragments that are deposited Compacted and cemented together Sandstone, conglomerate, and shale

Sedimentary Rock Features Stratification-layers Cross beds and graded bedding-slanting layers that form in sand dunes or river beds

More Features Ripple marks-caused by wind or water on sand before rock formation Fossils and concretions-lump of rock in sedimentary that has a different composition than the main rock geode

Metamorphic Rocks metamorphic rock - chemical processes or changes in temperature and pressure cause rocks to change Heat, pressure, and hot fluids cause some minerals to change into other minerals Minerals may change in size or shape, or separate into parallel bands that give the rock a layered appearance Hot fluids may flow through the rock and dissolve some materials and add others

Classification of Metamorphic Rocks Foliated- metamorphic rock texture with planes or bands Extreme pressure cause the mineral crystals in the rock to realign or regrow Also occurs as minerals that have different compositions separate produce alternating dark and light bands slate, schist, and gneiss

Nonfoliated -metamorphic rock texture without planes or bands Many nonfoliated metamorphic rocks have only one mineral or very small amounts of other minerals Other nonfoliated metamorphic rocks contain round or square grains unlikely to change shape or position marble and quartzite

Examples Marble Quartzite Gneiss