1. Unit 1 “Physical & Chemical World” Earth Layers/Tectonics/Soils Atmosphere Water

2. Layers of Earth Core- center, mostly iron
Inner core km thick, T & P cause iron to solidify
Outer core km thick, liquid iron, creates magnetic field
Mantle- 70% of earth’s interior, made of O, Si, Mg
Asthenospere- closest to core, gelatinous, where magma is formed
Upper mantle- cooler, more solid, brittle
Crust- outermost layer
Crust + upper mantle make up lithosphere

3. Plate Tectonics Tectonic plates- made of…
Uppermost mantle
Crust- 2 types:
Oceanic- thin (5-10 km), dense, rich in Fe, Mg, Si, below sea level
Continental- thick (20-70 km), less dense, rich in Ca, Na, K, Al
Constantly moving about 1-10 cm/year
15 major plates- We are on North American Plate

4. Plate Boundaries Where 2 plates meet 3 types of plate boundaries
“Ring of Fire” – Pacific Ocean

5. 1. Transform Boundaries
Plates slide past each other at transform faults
Movement is horizontal (strike-slip fault)
Mostly smooth movement
If stuck, pressure builds, causes earthquakes

6. 2. Convergent Boundaries
2 plates move toward each other
3 Types (next 3 slides)

7. a. OCEANIC - CONTINENTAL
Oceanic plate is forced under continental plate
Called subduction
Creates deep-sea trench
Creates volcanic mountains along continental plate.
EX: Peru-Chile Trench and Andes Mountains of South America

8. b. OCEANIC - OCEANIC
Oceanic plate is forced under another oceanic plate
Called subduction
Crust melts into mantle
Creates deep-sea trench
Creates arc of volcanic islands that parallel trench
EX: Mariana Trench & Mariana Islands
Aleutian Trench & Aleutian Islands

9. c.CONTINENTAL - CONTINENTAL
Two continental plates collide
Mountain ranges are created
EX: Himalayas- Indian plate forced under Eurasian plate

10. 3. Divergent Boundaries 2 plates move apart Creates rifts
Magma comes to surface & cools, creating crust
Usually in oceans, but can occur in continents (Africa’s Rift Valley)
Creates mid-ocean ridges
EX: Mid-Atlantic Ridge created when N.American plate pulls away from Eurasian plate.

11. CAUSES OF PLATE MOVEMENT
Convection currents
Hot mantle rises
Cools down
Cooled-down mantle sinks
Creates currents that move plates.

12. THEORY OF CONTINENTAL DRIFT
Alfred Wegner was first to propose theory of continental drift
He said:
All continents joined in large land mass called Pangea (Greek for “all land”)
Pangea began breaking up 200 million years ago.
Continents ended up where they are now
Continents are still moving

13. Evidence of Continental Drift
Fossils- similar plants & animals on widely separated continents
Rock Formations- similar rock types & stratification between 2 continents
Climate- Antarctica has coal deposits, indicating it had swamps, thus warmer weather= closer to equator

14. Earthquakes Epicenter- point where first movement occurs
Damage depends on soil underneath
Modern contractors build weak spots, pads/floats to absorb vibration
Underwater earthquakes cause tsunamis
Destroy coastal ecosystems
Saltwater infiltrates soil
sewage/industrial waste infect freshwater supplies

15. Tsunami
December 2004 – Sumatran Tsunami

16. Volcanoes Good Created land (fertile soil), atmosphere, oceans Bad
Release sulfur, combines with H20 to form sulfuric acid; interferes with solar radiation, cools climate (Mt. Pinatubo- Philippines)
Dust/Ash- can change climate by blocking sunlight (1815- Mt. Tambora in Indonesia, snowed in July in parts of New England, “year without a summer”)
Clouds of hot, toxic gases
Mudslides

17. The Layered Earth Mantle
Made of less dense materials
Oxygen, magnesium, silicon
Two regions:
Lower mantle - solid
Upper mantle or athenosphere - plastic and movable
Convection currents form in the athenosphere and are responsible for plate tectonics

18. The Layered Earth Crust
Also referred to as the lithosphere
Composition is less dense than lower layers
Skin of the physical planet
Two types:
Oceanic - higher density; basalts
Continental - lower density; granites

19. Rock Types
Rock Cycle - Cycle of creation, destruction, and metamorphosis.
Three major rock classifications:
Igneous
Sedimentary
Metamorphic

20. Igneous Rocks Most common type of rock in earth’s crust.
Solidified from magma extruded onto the surface from volcanic vents.
Quick cooling of magma produces fine-grained rocks.
Basalt (makes up ocean floor)
Slow cooling of magma produces coarse-grained rocks.
Granite

21. Sedimentary Rock
Formed by deposited materials that remain in place long enough, or are covered with enough material for compaction, may again become rock.
Among the three major types of rock, fossils are most commonly found in sedimentary rock. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remnants.

22. Metamorphic Rock
Pre-existing rocks modified by heat, pressure, and chemical agents.
Chemical reactions can alter both the composition and structure of rocks as they are metamorphosed.
Marble (from limestone)
Quartzite (from sandstone)
Slate (from mudstone and shale)

23. Weathering
Mechanical - Physical break-up of rocks into smaller particles without a change in chemical composition.
Chemical - Selective removal or alteration of specific components that leads to weakening and disintegration of rock.
Oxidation
Sedimentation - Deposition of loosened material.

24. Geological Boundaries

25. Effects of Agriculture on the Environment
Chapter 12
Effects of Agriculture on the Environment

26. “Clean Water Farms” Case Study
Intensive rotational grazing: is a system of grazing in which ruminant (animals that chew their cud) and non-ruminant herds are regularly and systematically moved to fresh pasture with the intent to maximize the quality and quantity of forage growth.
The herds graze one portion of pasture, or a paddock, while allowing the others to recover.
The grazers obtain the majority of their nutritional needs without the supplemental feed sources that are required in continuous grazing systems.

27. Many environmental problems result from agriculture:
Soil erosion
Sediment transport and deposition downstream
On-site pollution from fertilizers and pesticides
Deforestation
Desertification
Degradation of water aquifers
Salinization
Accumulation of toxic metals and organic compounds
Loss of biodiversity

28. The American Dust Bowl of the 1930s
Farming easily damages soils
Intensive plowing and major drought loosened the soil
The soil blew away during wind storms
Houses, cars, and farms were destroyed
Many farmers abandoned their farms
The Grapes of Wrath was first a novel made into a popular movie about the dust bowl

29. Must Know This! Click Here for Info On Almost Every Birthday Cakes
Rock!
Click Here for Info

30. Soil
Soil – complex mixture of weathered minerals materials from rocks, partially decomposed organic molecules, and a range of living organisms
Not dirt!
Soil is a living resource (“It’s alive!!!”), an ecosystem
Approximately 20,000 different types of soils in the U.S. alone
Building soil is a slow process!!
It takes thousands of years to form 1 mm deep soil

31. Soil Composition and Texture
45% mineral
Derived from parent material
Underlying bedrock
Deposition (i.e., glaciers, rivers, ocean currents, windstorms, landslides)
Other 55%
Air
Water
Organic matter from decomposition of organisms

32. Soil Composition and Texture
Particle size is critical
Larger particles = more pores of greater size
Pores give soil drainage and aeration
Loosely packed soils - good drainage and good aeration
Tightly packed soils – bad drainage and poor aeration

33. Soil Composition and Texture
Soil texture – the relative proportion of sand, silt, and clay in a soil sample
Mineral composition
Depending on a number of environmental factors, the soil can contain 0-100% OM
Humus – brown, insoluble residue from the breakdown of organisms
Provides nutrients
Development of structure and texture (facilitates soil clumping, maintains spacing between soil particles)

34. Soil Particle Sizes Classification Size (mm) Gravel 2 – 64 Sand
0.05 – 2
Silt
0.002 – 0.05
Clay
< 0.002

35. Soil Profiles
Soils are stratified into horizontal layers called soil horizons.
O Horizon (Organic layer)
Leaf litter, partially decomposed organisms.
Organic matter composition 20-30%
Decomposition of organic material forming humus
A Horizon (Topsoil)
Mineral particles mixed with organic material.
Most root activity
Most biological productive zone
Typically has a dark color (OM)
Referred to as topsoil

36. Soil Profiles E Horizon (Leaching Zone)
Soil horizons diagram
E Horizon (Leaching Zone)
Not present in all areas…In acidic soils
Depleted of soluble nutrients.
Weak organic acids typically dissolve and remove silicate clay, aluminum, and iron
Lighter color than A or B horizons
B Horizon (Zone of Accumulation)
Often dense texture from accumulating nutrients.
Well-developed examples are bright in color
C Horizon (Parent Material)
Least weathered rock fragments with little organic material.

37. Soil Texture Triangle
WATCH VIDEO!

38. Soil profile

39. Global Soil Degradation

40. If you need a refresher on soil or missed class…watch this video!
Click here!

41. Where Eroded Soil Goes: Sediments Also Cause Environmental Problems
Lots of soil is in water runoff that ends up in streams & rivers and then deposits it at the mouths of the rivers.
These deposits end of destroying some fisheries
Coral reefs are also being destroyed by sediments landing on them
Watch Video Here