1. Rocks and the Rock Cycle

2. Rock Divisions Rocks are divided into 3 categories based on how they were formed. – Igneous – Sedimentary – Metamorphic

3. Classifying Rocks When classifying a rock sample geologists observe texture, color, & mineral composition. – Texture: the size, shape, and pattern of the rock’s grain. – Color: the apparent color of the rock, on the inside and the outside. – Mineral composition: The minerals that make up the different parts of a rock.

4. Texture: Grain Size Fine vs. Coarse Grain Some rocks are considered coarse- grained (large grains) and some are fine- grained. Notice the difference in texture between the fine-grained slate and the coarse- grained diorite to the right.

5. Texture: Grain Shape Rounded vs. Jagged The grains in a rock vary widely in shape: ex: smooth and rounded = conglomerate jagged = breccia In some rocks, such as granite, the grain results from the shapes of the crystals that form the rock In other rocks, the grain shape results from fragments of other rock

6. Texture : Grain Patterns (flat, wavy, random) The grains in a rock often form patterns: – flat layers – wavy, swirling patterns – randomly occurring

7. Different Types of Texture Grain Size: Grain Shape: Grain Pattern:

8. Igneous Rock: “Fire Rock” Igneous rock forms when magma cools and makes crystals. There are 2 types of igneous rock: – intrusive – formed underground, where the magma cools slowly – extrusive - formed above ground, where the magma cools quickly

9. Sedimentary Rock Sedimentary rocks form from particles deposited by water and wind If you have ever walked along a beach (which I am sure you have) you may have noticed tiny sand grains, mud, and pebbles. These are some sediments that eventually form into sedimentary rocks

10. Lithification The process by which sediment becomes sedimentary rock Sedimentary rock forms in 4 steps: Step 1: erosion Step 2: deposition Step 3: compaction Step 4: cementation

11. Lithification Step 1: Erosion Destructive forces are constantly breaking up and wearing away all the rocks on Earth’s surface The forces include heat and cold, rain, waves, and grinding ice Erosion occurs when running water or wind loosens and carry away the fragments of rock.

12. Lithification Step 2: Deposition Deposition is when sediment settles out of the water or wind carrying it. In addition to particles of rock, sediment may include shells, bones, leaves, stems, and other remains of living things, which may eventually fossilize.

13. Lithification Step 3: Compaction Compaction occurs when thick layers of sediment build up and put pressure on the bottom layers. Year after year more sediment falls on top, creating new layers and further compacting the bottom ones. The layers often remain visible in the sedimentary rock.

14. Lithification Step 4: Cementation Cementation is when dissolved minerals crystallize and glue particles of sediment together. While compaction is taking place, the minerals in the rock slowly dissolve in the water. The dissolved minerals seep into the spaces between particles of sediment. The process of compaction and cementation takes millions of years.

15. Sedimentary Transformations Point A: water or wind deposits sediments Point B: The heavy sediments press down on the layers beneath Point C: Dissolved minerals flow between the particles and cement them together

16. Metamorphic Rock Metamorphic rock is sedimentary or igneous rocks that have "morphed" into another kind of rock. How do sedimentary and igneous rocks change? pressure & heat

17. Metamorphic Rock Pictures

18. Bet You Weren’t Expecting A…. POP QUIZ!!!!! Bet You Weren’t Expecting A…. POP QUIZ!!!!! 1.What are the three types of rock? 2.Which type of rock has been formed by magma or lava? 3.What do we classify rocks by? 4.How do sedimentary rocks form (in order)? 5.Metamorphic rocks are rocks that have ______________? (fill in the blank) 6.What is the process of sediments forming a sedimentary rock? 7.What does “ignis” mean in the word igneous? *Answers are on next slide!

19. ANSWERS!!!! ANSWERS!!!! 1.Igneous, Sedimentary, and Metamorphic 2.Igneous 3.Texture, Color, and Mineral Composition 4.Erosion, Deposition, Compaction, Cementation 5.Morphed 6.Lithification 7.“ignis” means fire

20. The Rock Cycle

21. Another Rock Cycle Picture…

22. The Rock Cycle Almost all rock that we have on Earth today is made up of the same stuff as the rocks that dinosaurs and other ancient life forms walked, crawled, or swam over While the stuff that rocks are made of has stayed the same, the rocks themselves have not Moving tectonic plates are responsible for destroying and forming many types of rocks Over time rocks are recycled into other rocks