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

2. GEOLOGIC TIME SCALE
Organizes Earth’s 4.6 billion years of history into subgroups
Subgroups:
Eons
Eras
Periods
Epochs
4 Major Eons…

3. 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

4. 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

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

6. Ring of Fire Video (short)

7. Hot Spot (Short)

8. 1. Transform Boundaries
Plates slide past each other at transform faults
Movement is horizontal (strike-slip fault)
To the left- sinistral
To the right- dextral
Mostly smooth movement
If stuck, pressure builds, causes earthquakes

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

10. 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

11. 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

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

13. 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.

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

15. 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

16. 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

17. 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

18. Tsunami
December 2004 – Sumatran Tsunami

19. 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

20. 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

21. 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

22. Plate tectonics 7 major plates, many smaller plates
Moving relative to one another; average speed of a few inches per year
3 types of boundaries between plates:
Convergent
Divergent
Transform-fault
See

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

25. 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

26. Sedimentary Rock
Formed by deposited materials that remain in place long enough, or are covered with enough material for compaction, may again become rock.

27. 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)

28. 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.

30. Geological Boundaries