1. CHANGING EARTH Rocks, fossils, earthquakes, volcanoes

2. Rocks and Minerals  Most rocks are composed of minerals  Descriptive terms about minerals found in rocks  Shape  Color  Luster  Texture  Hardness

3. Igneous Rocks  Froms from magma (below ground) or lava (above ground)  Has crystals  Classified by  Origin  Texture  Mineral Composition

4. Igneous Rocks  Origin  Extrusive Formed above ground Basalt  Intrusive Formed below ground Granite

5. Igneous Rocks  Texture  Depends on size and shape of minerals (if present)  Rapidly cooling lava forms fine-grained rocks with small crystals  Slowly cooling magma forms course-grained rocks with large crystals  Does intrusive or extrusive rock have larger crystals?  Intrusive, it takes longer to cool so there is more time for the crystals to grow

6. Igneous Rocks  Mineral composition  Silica is found in magma and the quantity varies.  Low-silica magma forms rocks that are dark in color.  High-silica magma forms rocks that are light in color.  Different minerals determine colors in the rock

7. Sedimentary Rocks  Sediment is small, solid pieces of material that come from rocks or living things.  Formed from other rock and exposed to forces that wear away Earth’s surface.  Erosion – breaking up of rocks due to wind, running water, ice (glaciers)  Deposition – particles broken down by erosion are deposited as loosely packed sediment  Compaction – process that presses sediments together  Cementation – while compaction is taking place, minerals slowly dissolve in the water. The dissolved minerals crystallize & glue particles of sediment together.

8. Types of Sedimentary Rock  Clastic  Rock fragments are squeezed together. Fragments may be microscopic or large Shale, sandstone  Organic Forms from the thick layered remains of plant and/or animals  Coal, limestone  Chemical Crystallized minerals that dissolve in a solution Rock salt

9. Metamorphic Rocks  Heat and pressure deep beneath the Earth’s surface can change any rock into a metamorphic rock  High temperatures change the size and shape of the grains and crystals  Classified according to the arrangement of the grains that make up the rock

10. Types of Metamorphic Rocks  Foliated  Grains arranged in parallel layers or bands, may split into layers  Slate  Nonfoliated  Mineral grains arranged randomly, does not split into layers  Marble

11. Bookwork  Mass movement of landforms  Gravity plays a role  Water plays a role  Water erosion by rivers, ect  How does the speed of the water affect the amount and size of particles moved?  Movement of rocks  The further a boulder moves down steam, the smaller it gets. Why?

12. Bookwork  Glaciers  Leave behind U-shaped valleys  Move the most material over time  Form when more snow falls and melts  Waves  Ocean waves are created by wind on the surface  Water particles move up and down, but not in any other direction  Wear down beaches and rocks

13. Rock Cycle  What process leads to the formation of sediment?  Erosion!  How is weathering related?  What is soil sediment? How is it formed?  Weathering and erosion of rocks into smaller and smaller pieces makes soil

14. Soil Formation  Soil is made of tiny pieces of eroded rock and HUMUS  HUMUS is a mixture of organic material. It comes from broken down plant and animal matter  Majority of HUMUS comes from earthworms  The higher the HUMUS content, the better the soil

15. Rock Cycle  Three main types of Rocks:  Sedimentary, Metamorphic, Igneous  Energy used to form or change rocks:  Heat & Pressure (melting, etc)  Processes used to change rocks:  Erosion, weathering, deposition, cementation, melting

16. Rock Cycle Metamorphic Igneous Sedimentary Igneous Metamorphic Sedimentary

17. Rock Cycle Diagram  Copy the diagram of the rock cycle from page F 71

18. Age of Rocks  How do scientists determine the age of rocks?  This age is often referred to as “relative age,” why?  For very old rocks, scientists typically use a process called carbon dating to determine their relative age. This process is based on the assumption that carbon has degraded at a particular rate for the entire history of the Earth.  Are the oldest rocks always at the bottom of the layers?  How could older rocks end up on top of younger rocks?

19. Folding & Faulting  The Earth’s surface goes through folding and faulting which pushes and turns the rock layers.  At fault lines, there will be noticeable “movement” in the rock layers. Pg G119  Earth’s surface is constantly changing and this can include the rock layers, especially at fault lines

20. Rock Layers Practice

21. Fossils  An index fossil helps to date rocks.  Must be widely distributed  Must represent an organism that existed briefly  Tell the age of the rock based on when the fossil occurred

22. Fossils  How are fossils formed?  Die, sediments are deposited on top, compact down, pressure eventually cements all and turns the bones into rock  Will everything that dies turn into a fossil?  What type of rock are fossils found in?  Sedimentary, sometimes in metamorphic  How do fossils show evidence of the changing surface of the Earth?  Moving sediments, changing species, and?

23. Fossils, con’t  Why are more recently deposited rock layers more likely to contain fossils resembling existing species than older rock layers?  Older fossils tend to represent species that are extinct  If an old fossil looks like a modern organism, what can you conclude?  The evolutionary rate of the organism is slow.