WHAT ARE ROCKS? ROCKS are a naturally occurring SOLID MIXTURE of one or more minerals and organic matter. Rocks are ALWAYS changing.

WHAT ARE ROCKS? ROCKS are a naturally occurring SOLID MIXTURE of one or more minerals and organic matter. Rocks are ALWAYS changing.

How do we classify Rocks? Formation (where and how the rock was formed) Texture (grainy, glassy) Composition (what minerals make up the rock)

From the Latin word igni (fire) Form from the cooling of molten rock (lava and magma). What are Igneous Rocks? The most abundant type of rock. Classified according to their origin and composition.

Classification 1 ORIGIN Where are Igneous Rocks are formed

How does Extrusive Igneous Rocks form? (Think Exit) Extrusive Rock is formed from lava erupted onto Earth s surface. Exits the Earth- thus it is lava that is cooling. Cools quickly before large crystals can form. Will have fine-grained, small crystals. Extrusive rocks are smooth Ex. (Basalt)

How does Intrusive Igneous Rocks form? (Think inside) Intrusive Rock is formed when magma hardens beneath Earth s surface. Magma cools slowly inside of the earth. Slow cooling causes the formation of Coarse-Grained rocks with large crystals. Intrusive rocks usually have a rough texture. Ex. Granite

What is Lava? molten material found on the surface of the earth. What is Magma? molten material found beneath the surface of the earth.

Obsidian has a glassy texture

Rhyolite has a fine-grained texture

Mafic describes dark colored igneous rocks. What does Mafic describe? What does Felsic describe? Mafic rocks have a low amount of silica, but a higher amount of iron, magnesium, or calcium. Felsic describes light colored igneous rocks. Felsic rocks contain a high amount of silica.

Rocks made from sediments that are pressed or cemented together or when sediments precipitate out of a solution. What are sedimentary rocks? Sedimentary rocks represent 7% of the Earth s crust, but they cover 70% of the Earth s surface. There are 3 types of sedimentary rock. Sedimentary rocks are fossil-carrying rocks.

What are sediments? Rock fragments, mineral grains, animal & plant remains-shells, bones, leaves, stems

Where do Sedimentary rocks form? Form at or near the surface of the earth = no internal heat Visual Clues that it is sedimentary rock. The rock will have layers (strata)

What are Strata? Horizontal layers found in sedimentary rocks. Layers at the top are the youngest (newest), layers at the bottom are older.

Newer layers Older layers

How does Sedimenta ry rock form? W Weathering E Erosion D Deposition C Compaction C Cementation the breaking down of material by wind, water, ice, sunlight, & gravity Movement of sediment Where the sediment is deposited. As new layers of sediment occur, the weight of the new layers can squeeze the older sediment tightly together. (mush) Dissolved minerals flow between the particles and glue them together

Classification 2 Formation How are Sedimentary rocks formed. There are 3 types of Sedimentary Rock

What are the three types of sedimentary rock? Clastic: (Rock & mineral fragments compacted & cemented together) Chemical: (solutions of dissolved minerals & water) Organic: Form where the remains of plants and animals are deposited in thick layers (Contain remains, fossils of ocean animals)

Rocks that have changed due to intense temperature and pressure What is metamorphic rock? Meta means change and morphosis means form in Greek Igneous, sedimentary and other metamorphic rocks can change to become metamorphic rocks.

What occurs in the Earth to change these rocks? Pressure from overlying rock layers. High heat, but not enough to melt the rock. Rocks may be flattened or bent or atoms may be exchanged to form new minerals.

How are Foliated mineral grains are flattened and line up in parallel bands. metamorphic rocks classified? Non-Foliated No bands are formed.

Foliated Non Foliated