Chapter 4: Rocks

What is a rock? A ROCK is a mixture of minerals, mineraloids, glass, or organic matter.

3 Main Categories of Rocks 1.Igneous Rocks 2.Metamorphic Rocks 3.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 Granite Pumice Obsidian 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 - foliatedQuartzite – 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 Shale - detritalLimestone - chemical Coquina - organicSandstone - detrital Coal - organic Conglomerate - detrital