What is a rock? • A ROCK is a mixture of minerals, mineraloids, glass, or organic matter.
3 Main Categories of Rocks • Igneous Rocks • Metamorphic Rocks • Sedimentary Rocks
Rock Cycle • The process by which, over many years, Earth materials form and change back and forth among igneous rocks, sedimentary rocks, and metamorphic rocks. * The rock cycle can start with any rock – it is a cycle
Processes of the Rock Cycle Weathering-breaking of rocks into smaller pieces, either mechanically or chemically Erosion-the process that wears away surface materials and moves them from one location to another, usually by gravity, glaciers, wind, or water. Compaction-pressing sediments of rock together Cementation-sediments naturally being glued together Sediments-made from loose rock fragments
Igneous Rock Vocabulary • Igneous Rock-most abundant rock on Earth because its inside and outside the earth, formed from magma and lava • Intrusive-forms inside the earth from magma • Extrusive-forms outside the earth from lava
Granitic-magma is light colored, light weight, low density rocks like Pumice and Granite (Silicon,Oxygen) • Andesitic-magma is of medium color and density, characteristics of both Basaltic and Granitic • Basaltic-magma is dark colored, heavy rich in Iron and Magnesium, higher density. *Density is how highly packed a substance’s molecules are. Mass/Volume.
Igneous Rock Examples Obsidian Granite Pumice Scoria
Facts about some Igneous Rocks • Basalt – has iron in it and contains some air pockets. • Pumice – is porous, and less dense than water so it will float. • Obsidian – is glass like.
Minerals that make up Granite… • Feldspar • Quartz • Mica • Hornblend • and others.
Metamorphic Rocks • Metamorphic-rocks that have changed due to heat and pressure • Foliated- type of metamorphic rock created when mineral grains flatten and line up in parallel bands • Nonfoliated-type of metamorphic rock created when mineral grains change, grow, and rearrange – but do not form bands.
Metamorphic Rock Examples Slate - foliated Marble – nonfoliated Gneiss - foliated Quartzite – nonfoliated
Sedimentary Rocks • Sedimentary Rocks-form when sediments get pressed or cemented together (Cementation and Compaction) • Organic-made from the remains of once living things. • Detrital/Clastic-made from broken rock fragments. They have texture. • Chemical-when minerals precipitate out of a solution or left behind when a solution evaporates.
What is a Conglomerate? • Conglomerate – sedimentary rock made of large well-rounded stones that have been cemented together.
Sedimentary Rock Examples Coal - organic Shale - detrital Limestone - chemical Coquina - organic Conglomerate - detrital Sandstone - detrital