There are 3 Major Rock Groups

Rocks are made of minerals and make up Earth’s solid crust There are 3 Major (Geologic) Rock Groups Not the Rolling Stones, Kiss, or Van Halen 1. Igneous Rock 2. Sedimentary Rock 3. Metamorphic Rock Rocks are made of minerals and make up Earth’s solid crust

Basalt lava (glowing rock) oozes over basalt lava flow A. Igneous Rock -Forms when a hot molten liquid below ground, called magma, or above ground, called lava, “crystallizes” --meaning cools and solidifies. (FYI: Most of the continental crust is igneous rock.) Magma forms 3 ways: Rock is heated Pressure released Change composition Holt Online Visual: Comparing Int. & Ext Igneous Rocks Basalt lava (glowing rock) oozes over basalt lava flow

1. Intrusive Igneous Rock -Cools & crystallizes inside Earth -Slow cooling=large (coarse) crystals form

2. Extrusive Igneous Rock -Forms on surface (exterior) of Earth -Fast cooling=small (fine) or no crystals form

Texture of Igneous Rock -Slow cooling forms large crystals. (Coarse-grained Texture) -Fast cooling forms small crystals. (Fine-grained Texture)

Igneous Rocks Rock ID practice Use the rock key to identify the various rocks on your table: Igneous Rocks Classified according to composition & texture Glassy- shiny and looks like glass, does not have crystals. Ex: obsidian (volcanic glass)

Fine-grained-made of interlocking crystals. Ex: basalt - the most common extrusive igneous rock Crystals are not that easy to see. BASALT

More Igneous Rocks… Course Grained Texture= Granite

More Igneous Rocks… Porous- no crystals, cools rapidly, looks like a sponge. Gas bubbles formed in the molten liquid and then “froze”. Ex: pumice

B. Sedimentary Rock *There are 3 types of sedimentary rocks. *Often times, sand, mud, pebbles, or shells settle out in wind and water, get compacted and/or cemented together, and harden into rock. Here, rocks hardened in layers called strata from a process known as… stratification.

Three Types of Sedimentary Rock 1. Clastic -forms when rock or mineral fragments are cemented together.

2. Chemical forms when minerals crystallize out of a solution, such as sea water, to become rock.

3. Organic forms from the remains of once-living plants and/or animals 3. Organic forms from the remains of once-living plants and/or animals. (can contain visible fossils) Ex: Limestone Coal Chalk

C. Metamorphic Rock -Rocks that have undergone a change in texture, structure, or composition. -Changes in heat and pressure cause rocks to change from one form to another.

Textures of Metamorphic Rock Foliated the texture of metamorphic rock in which the mineral grains are arranged in layers or bands of color.

Nonfoliated -The texture of metamorphic rock in which the mineral grains are not arranged in layers or bands of colors.

Rocks are made, destroyed, and created again, from processes along the Rock Cycle.

Rock Cycle Quiz Melting Cooling Weathering & Erosion What process forms magma from solid rock? What process forms a rock from lava? What processes form sediment from solid rock? What processes form a Sedimentary Rock from sediment? What is the resulting rock type when an igneous rock changes because of added heat & pressure? What is the resulting rock type when magma cools & crystalizes? Melting Cooling Weathering & Erosion Compaction & Cementation Metamorphic Igneous