EPIC WEATHERING AND EROSION REVIEW FOR 6TH GRADE LET'S GOOOOO

1. EPIC WEATHERING AND EROSION REVIEW FOR 6TH GRADE LET'S GOOOOO

2. What even is a rock? • Elements + chemical compounds → hard, solid materials of Earth's surface • Minerals • Elements and compounds found in rocks • All minerals are solid

3. Weathering • chemical or mechanical • breaking down of rocks by exposure to air, moisture, organic materials • small-scale, local changes on rocks

4. Mechanical/Physical Weathering • breaks rocks into smaller pieces without changing them chemically • frost wedging, plants, animals, gravity

5. Frost Wedging • Water seeps into cracks in rock and freezes • When water freezes, it expands and breaks the rock

6. Living Organisms • Growing roots put pressure on rock • Burrowing loosens and weakens rock

7. Gravity • Exposes new surfaces for physical and chemical weathering • Avalanches, rock slides

8. Chemical Weathering • decomposition of rock due to chemical reactions between rock and chemicals in the environment • changes chemical composition of rock • materials acted upon

9. Chemical Weathering, cont'd • natural acids and oxygen • water + carbon dioxide = carbonic acid • acid rain – caused by pollution • sulfur released into air by factories, combines with water

10. Erosion • rock and soil materials are loosened and transported from one place to another • KEY = MOVEMENT • large-scale changes over great distances • From canyons and valleys all the way to • deltas and sand dunes

11. Wind • sand grains carried by strong winds act like sandpaper • scrape away little pieces of rock and soil from hills and mountains • can pick up soil from plants or fields and transport to other areas

12. Water • Runoff: water that flows over Earth's surface • Carries sediment, soil → eroding land

13. Water, cont’d • Three factors influence amount of water erosion: • Rainfall intensity and runoff – more rain, more erosion • Steepness of slope – steeper slope, more erosion • Vegetation/obstacles – more rocks and plants, less erosion

14. Soil • mixture of weathered rock, organic matter, and water • sand, gravel, humus • end result of weathering and erosion • humus - organic component of soil • comes from decomposing plant and animal • material

15. Structure of Earth • Crust: surface of Earth • Mantle: semi-solid middle layer • Convection currents in mantle cause movement of tectonic plates • Core: middle of Earth, iron and nickel • Extreme heat and under extreme pressure

16. Convection Currents • Convection currents: hot material rises and cool material sinks • CC in the mantle force materials up onto the Earth’s crust • Creates new crust, pushing tectonic plates into one another • This causes continental drift!

17. Rock Types • Igneous rock: formed by the cooling of lava or magma • Sedimentary rock: rock formed when sand, mud, and pebbles are deposited on top of each other • Layers squashed into each other until they form rock • Metamorphic rock: changed • by extreme heat and pressure

18. Steps 1-3 of the Rock Cycle • Molten rock from the mantle rises to the surface and creates new crust • - This molten rock cools and forms igneous rock • As a result of weathering, rock breaks down • Over time, broken down rocks are layered on top of each other to form sedimentary rock

19. Steps 4-7 of the Rock Cycle • As more and more rock builds up, pressure and temperature • increase a lot • This increased pressure and temperature form metamorphic rock • Metamorphic rock sinks into the mantle and melts into • magma, becoming part of the mantle • Through convection, the magma is pushed back up to • the surface and creates new igneous rock • AND THE CYCLE REPEATS

20. Rock Cycle Diagram