Rocks and the Rock Cycle

Rock Classification Rocks are classified by: How they form Texture Grain size Mineral composition Conglomerate Sedimentary Rock

Three Types of Rocks Igneous Sedimentary Metamorphic Schist

Igneous Rocks Hard and Durable Uses – building material Igneous rock: forms when molten rock (magma) cools and hardens Classified by: Where they form Crystal (grain) size Hard and Durable Uses – building material Basalt

Intrusive Igneous Rock Intrusive igneous: cooling takes place slowly beneath Earth’s surface (magma hardened beneath the surface of the Earth) Forms coarse grained rocks with large crystals Ex: granite, pegmatite granite

Extrusive Igneous Rock Extrusive igneous: cooling takes place rapidly on Earth’s surface (lava that erupted onto Earth’s surface) Forms fine grained rocks with small or no crystals; glassy texture Ex: basalt, rhyolite Pumice

Sedimentary Rock Sedimentary rock: forms from the compaction and/or cementation of sediments This process is called lithification Sediments are: Rock pieces Mineral grains Shell fragments Limestone

How do sediments form? weathering Sediments form through the processes of weathering and erosion of rocks exposed at Earth’s surface erosion

Sedimentary Rock con’t…. Sedimentary rock can also form from the chemical depositing of materials that were once dissolved in water When water evaporates, minerals left behind form rock gypsum Ex: shale, sandstone Uses: tools and building materials

Metamorphic Rock Metamorphic rock: forms when any rock type is changed into a different kind of rock Changes due to great heat and/or pressure Uses: statues and buildings Gneiss

Metamorphic Cont. Foliated – describes thin, flat layering Ex: slate, gneiss Nonfoliated – grains arranged randomly Ex: marble

How does rock change? Rocks are heated, squeezed, folded, or chemically changed by contact with hot fluids The deeper the rock is buried, the higher the pressure on the rock marble

The Earth Recycles Rock The rock cycle is an ongoing series of processes inside Earth and on the surface Slowly changes rocks from one kind to another Any type of rock can change into another type

Rocks Foldable Three tabs: Type of rock How they form At least 2 examples

Rock Cycle Poster Draw a colorful diagram of the rock cycle; make sure to include: 3 types of rocks Erosion and weathering Sediments Compaction and cementation Magma Melting Heat and pressure

Test Your Skills   Bed Based on the processes shown in the diagram, which type of rock is formed at #1?   A.              A. Sedimentary B.              B. Igneous C.              C. Metamorphic D.              D. Clastic   Because heat and pressure are needed to form #3, it must be what type of rock? A.     Sedimentary B.     Igneous C.     Metamorphic D.     Clastic

Cementation and compaction (lithification) Heat and pressure Weathering, transportation(erosion), and deposition Cooling and solidification Melting