A ROCK IS A naturally occurring, solid, mixture of one or more minerals or organic matter Rocks are Classified into 3 groups based on how they are formed: igneous, sedimentary, and metamorphic

Texture and composition give clues as to how rocks are formed, and are used to classify rocks Rocks are always changing form in a cycle called the Rock Cycle

Coarse Medium Fine Rock Classification Composition Texture the type of minerals a rock contains Composition the size, shape and arrangement of the minerals that make up a rock. Can be fine, medium, or coarse. Texture Medium Fine

The Rock Cycle The main idea of the rock cycle is that rocks are continually changing from one type to another and back again The elements that make up a rock are never created or destroyed - instead, they are constantly being recycled.

Types of Forces That Create Rocks Constructive Builds something up or creates something new Destructive Breaks something down or destroys something Explain how something can be BOTH…

In your notes… Definition Origin/Formation Classes/Groups   Definition Origin/Formation Classes/Groups Method for Grouping Other Info/ Example Igneous Sedimentary Metamorphic

Igneous Rock Form when magma cools and hardens. Sometimes look shiny and glasslike if lava cools quickly Sometimes have tiny holes and spaces if gas is trapped in the rock as it cools Two examples are: Basalt and Obsidian

Igneous Rocks Classes Extrusive rocks- formed by cooling lava Texture: glassy (obsidian) porous (pumice) fine-grained (basalt) Intrusive rocks- formed by cooling magma coarse-grained (granite)

Formation of Intrusive Igneous Rock

Obsidian… Basalt…

Granite… Coarse Grained Texture Pumice… Porous Texture

Sedimentary Rock Formed from particles called sediments Fairly soft and break easily Contain sand, pebbles, stones, and is the only rock to contain fossils Form at or near Earth’s surface Most have layers or strata

Sedimentary Process 1. Weathering (breaking down of rock) 2. Erosion (movement of sediments) 3. Deposition (collection of sediments) 4. Compaction & Cementation

Weathering- determined by rock type and climate Chemical Weathering: Mechanical Weathering Root Action Frost Action Moss

(By the way…)

Five Agents of Erosion Gravity Wind Running water Glaciers Waves

Examples of Deposition Nile River Delta Lateral moraine Cape Cod

Compaction & Cementation

3 Sedimentary Rock Types Clastic: sediment fragments cemented together by minerals Ex: Conglomerate Organic: form from the remains of animals or plants Ex: Coal Chemical: solutions of dissolved minerals & water (evaporation) Ex: Rock Salt

Metamorphic Rock Formed under the surface of the Earth due to extreme heat and pressure Have ribbon-like layers and may have shiny crystals formed by minerals cooling slowly over time Two examples are: Gneiss and Marble

Think about CAKE BATTER in an oven… Metamorphic Rocks Think about CAKE BATTER in an oven… Formed by tremendous heat & pressure, and chemical reactions inside the crust. Formed from all three rock types.

Types of Metamorphic Rock Slate Foliated (bands or layers) Ex: schist, slate, gneiss Gneiss Schist

Types of Metamorphic Rock Unfoliated (no bands or layers) Ex: marble and quartzite Quartzite

Warm-up: How are igneous rocks formed? What’s the difference between extrusive and intrusive igneous? What would their textures most likely look like?

Now: Complete the Rock Cycle Interactive with your partner Study for the Quiz tomorrow Work on the Green review for Thursday (test next Tuesday) Work on choice items for conference before Friday

Summary

Warm-up: List as many steps of the rock cycle as you can without using notes. What is the main idea of the rock cycle? Explain how rock is continually recycled in the rock cycle.

Warm-up: Describe how ALL sedimentary rocks in general are formed. What are the 3 subtypes of sedimentary rocks? What is the difference between weathering and erosion?