1. APES Test Review The Earth Chapter 1

2. Geologic Time Scale Two time scales – Geologic= based on rock layering and evolution – Radiometric= based on radioactive decay of rocks Time periods defined by major geologic events – Ex) mass extinctions Eons  eras  periods  epochs  stages

3. Key principles of Geologic Time Scale 1.Rock layers are laid down in strata= a slice of time 2.Superposition= the stratum above is younger than the one below

4. Complications of the Geo Time Scale 1.Strata is often eroded, distorted, tilted, or inverted 2.Strata from same time has different appearance 3.Only part of earth’s history from that time

5. Earth’s Structure Earth formed 4.6 bil years ago 3 rd planet from the sun Earth – Biosphere – Hydrosphere – Internal structure

6. Internal structure of earth Inner core Outer core Mantle Crust Lithosphere

7. Crust.05% of total mass of earth – 2 main parts Basalt rich ocean crust Granite rich continental crust – Continental crust From surface down 20-30 miles – Oceanic Crust Surface down 7 miles Found in ocean basins where water is 2 miles deep

8. Crust MOHO – Mohorovicic discontinuity Boundary between crust and mantle Mantle – Most of earth’s mass – Iron, magnesium, Al, Si-O compounds – 1800°C + Core – Mostly made of iron – Molten, but under so much pressure it is solid

9. Plate Tectonics Rose from two observations – Continental drift 1915 Alfred Wegner Pangaea started to break 200 mya Factors: biogeography, glacial landscapes in non-tundra, puzzle piece continents, similar rocks – Seafloor spreading 1960’s magnetic properties of seafloor rock noticed Moving away from ridge on floor rocks got older

10. Boundaries Transform Divergent Convergent

11. Earthquakes Richter Scale – Minor- 3.0-3.9 – Extreme 9.0+ Severity depends on: – Amount of stored potential energy – Distance rock moved when energy released – How far below surface mvt occurred – Type of rock material

12. Volcanoes Produce magma= melted rock, Sulfur dioxide, steam, HCl – Sulfur dioxide effects climate; reflect shorter wavelengths of radiation Can be – Intermittent – Dormant – Extinct Majority occur at subduction zones and mid- oceanic ridges

13. Mount St Helens Washington State Erupted 1980 Removed trees, increased soil erosion, destroyed wildlife, polluted air Mudflows, melted glaciers, clogged rivers 57 people killed

14. Mount Pinatubo West coast of Philippines 1991, June Erupted for 9 hrs 18 mil metric tons of Sulfur Dioxide – In atmosphere for 3 weeks – Largest amount to date – Caused a 1°C cooling of earth after 3 years

15. Types of Volcanoes Fissure Shield Dome Ash cinder Composite Caldera

16. Seasons, solar intensity, latitude Factors that effect amount of solar energy – Earth’s rotation (24 hrs) – Revolution (365 days) – Tilt of axis 23.5° – Atmospheric conditions Earth is closest in Jan each yr Farthest away in july – Seasons are not caused by distance from the sun

17. Soil A good soil should: – 45% minerals w/ sand, silt, clay – 5% organic matter – 25% air – 25% water How soil develops: – Parent material, climate, living organisms, topography

18. Soil Profile O horizon= surface litter A horizon=topsoil E horizon= zone of leaching B horizon=subsoil C horizon= weathered parent material bedrock

19. Soil Components Clay – Fine particles, Compacts easy, Low permeability of water Gravel – Coarse particles, rock fragments Loam – Equal clay, sand, silt, and humus, rich in nutrients Sand – Coarser than silt, water flows through quickly, good for plants that don’t need a lot of water Silt – Size in between sand and clay, easily transported by water

20. Fertilizers Organic – Manure, green manure, compost – Improves soil texture, adds nitrogen, bacteria, and fungi – Improves ability to hold water – Prevent erosion Inorganic – does not add to humus, less ability to hold water, lowers O2 content, only limited # of nutrients, a lot of energy to make, releases N20

21. Erosion Sheet erosion – Horizontal layer Rill erosion – Fast flowing water cuts small channels in soil Gully Erosion – Channels increase in size and depth

22. Soil Erosion Desertification – Prod falls 10% – Due to human/climate change Salinization – Water isn’t absorbed, evaporates leaving behind salts Waterlogging – Saturation of soil w/ water – Increase in water table

23. Rock Cycle