1. GEOLOGY and the Rock Cycle

2. GEOLOGIC PROCESSES
The earth is made up of a core, mantle, and crust and is constantly changing as a result of processes taking place on and below its surface.
The earth’s interior consists of:
Core: innermost zone with solid inner core and molten outer core that is extremely hot.
Mantle: solid rock, under which is the asthenosphere that is melted pliable rock.
Crust: Outermost zone which underlies the continents. (Lithosphere)

3. Tectonic plate Inner core
Spreading center
Collision between two continents
Oceanic tectonic plate
Ocean trench
Oceanic tectonic plate
Plate movement
Plate movement
Tectonic plate
Oceanic crust
Oceanic crust
Subduction zone
Continental crust
Continental crust
Material cools as it reaches the outer mantle
Cold dense material falls back through mantle
Hot material rising through the mantle
Mantle convection cell
Figure 15.3
Natural capital: the earth’s crust is made up of a mosaic of huge rigid plates, called tectonic plates, which move around in response to forces in the mantle.
Mantle
Two plates move towards each other. One is subducted back into the mantle on a falling convection current.
Hot outer core
Inner core
Fig. 15-3, p. 337

4. INTERNAL GEOLOGIC PROCESSES
Huge volumes of heated and molten rock moving around the earth’s interior form massive solid plates that move extremely slowly across the earth’s surface due to convection currents.
Tectonic plates: huge rigid plates that are moved with convection cells or currents by floating on magma or molten rock.

5. Oceanic crust (lithosphere) Abyssal plain Continental slope
Folded mountain belt
Volcanoes
Abyssal plain
Abyssal floor
Oceanic ridge
Abyssal floor
Abyssal hills
Trench
Craton
Oceanic crust (lithosphere)
Abyssal plain
Continental slope
Continental shelf
Continental rise
Mantle (lithosphere)
Continental crust (lithosphere)
Mantle (lithosphere)
Figure 15.2
Natural capital: major features of the earth’s crust and upper mantle. The lithosphere, composed of the crust and outermost mantle, is rigid and brittle. The asthenosphere, a zone in the mantle, can be deformed by heat and pressure.
Mantle (asthenosphere)
Fig. 15-2, p. 336

6. Earth orbit: 149,600,000 km (1.00 AU) from Sun diameter: 12,756.3 km
mass: 5.972e24 kg
Earth’s layers (depths in km)
0- 40 Crust
Mantle
Outer core
Inner core

7. Earth Earth’s mass (measured in 10^24 kg) atmosphere = 0.0000051
oceans =
crust = 0.026
mantle = 4.043
outer core = 1.835
inner core =

8. Earth’s Interior Core is made up mostly of iron/nickel
Temperatures in core reach 7500 K
The crust is primarily quartz.
Taken as a whole, the Earth's chemical composition (by mass) is:
34.6% Iron % Nickel
29.5% Oxygen 1.9% Sulfur
15.2% Silicon % Titanium
12.7% Magnesium

9. The Earth’s Major Tectonic Plates
Figure 15-4

10. Major Plates North American Plate South American Plate Antarctic Plate
Eurasian Plate
African Plate
Indian-Australian Plate
Nazca Plate
Pacific Plate

11. Plate Movement
The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart at divergent plate boundaries and slide past at transform plate boundaries.
Figure 15-4

12. Figure 15.4
Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on?
Fig. 15-4, p. 338

13. INDIA-AUSTRALIAN PLATE
EURASIAN PLATE
NORTH AMERICAN PLATE
ANATOLIAN PLATE
JUAN DE FUCA PLATE
CARIBBEAN PLATE
CHINA SUBPLATE
ARABIAN PLATE
AFRICAN PLATE
PHILIPPINE PLATE
PACIFIC PLATE
SOUTH AMERICAN PLATE
NAZCA PLATE
INDIA-AUSTRALIAN PLATE
SOMALIAN SUBPLATE
Figure 15.4
Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on?
ANTARCTIC PLATE
Divergent plate boundaries
Convergent plate boundaries
Transform faults
Fig. 15-4a, p. 338

14. Transform fault Rising magma
Trench
Volcanic island arc
Craton
Transform fault
Lithosphere
Rising magma
Subduction zone
Lithosphere
Lithosphere
Asthenosphere
Asthenosphere
Asthenosphere
Figure 15.4
Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on?
Divergent plate boundaries
Convergent plate boundaries
Transform faults
Fig. 15-4b, p. 338

15. Convergent Plate Boundary
Two plates pushed together
Oceanic + Continental = Subduction Zone
Oceanic + Oceanic = Trench
Continental + Continental = Mountain Range

16. Divergent Plate Boundary
Plates moves apart from one another
Oceanic plates form oceanic ridges

17. Transform Faults
Plates slide and grind past one another along a fracture in the lithosphere

18. Benefits of volcanoes, earthquakes, and tsunamis
Geological:
Recycle rock and earth’s crust
Form minerals
Ecological:
Speciation (due to isolation)
Maintaining atmosphere thus climate
Enrich soils = more food

19. Geologic Time Scale
~4.6 billion years ago: Earth believed to have formed, hot ball of rock
3.9 billion years ago: rainstorms
3.5 billion years ago: oceans, first living organisms

20. Geologic Eras
Precambrian Era: 4.6 billion years ago- 545 million years ago
87% of Earth’s history
Prokaryotes dominated
First eukaryotes appeared ~ 1.5 billion years ago
Simple multicellular organisms in seas
Paleozoic Era: 545 million years ago – 248 million years ago
“Explosion of life”
Many types of invertebrates in shallow seas
Early: earliest vertebrates
Middle: amphibians
Later: reptiles

21. Geologic Eras
Mesozoic Era: 248 million years ago – 65 million years ago
Triassic: mammals made first appearance
Jurassic: “age of dinosaurs”
Cretaceous: radiation of mammals and evolution of flowering plants
Plate Tectonics: continental shift
Cenozoic Era: 65 million years ago – now
Mammals flourish
Primates evolve
Extinctions affect diversity
Modern human species evolved ~200,000 years ago

22. EXTERNAL GEOLOGIC PROCESSES
Surface processes
Based largely on energy from the sun and gravity
Tends to wear down Earth’s surface and produce a variety of landforms by the buildup of eroded sediment
Erosion
Weathering

23. Wearing Down and Building Up the Earth’s Surface
Weathering is an external process that wears the earth’s surface down.
Figure 15-6 23

24. EROSION
Process by which material is dissolved, loosened or worn away from one part of the earth’s surface and deposited in other places
Streams are most important agents of erosion

25. MINERALS, ROCKS, AND THE ROCK CYCLE
The earth’s crust consists of solid inorganic elements and compounds called minerals that can sometimes be used as resources.
Mineral resource: is a concentration of naturally occurring material in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost. 25

26. Nonrenewable mineral resources
Fossil fuels (oil, natural gas, coal)
Metallic minerals (Al, Cu, Fe)
Nonmetallic minerals (sand, gravel, limestone)

27. Minerals and their Uses
Metals
Nonmetals
Al- building, cans
Steel- building
Cu- conductor, electronics
Mn, Co, Cr- used in alloys
Pt- catalytic converters
Sand- glass, concrete, bricks
Gravel- roadbeds
Limestone- roadbeds, natural buffer
Phosphate salts- fertilizers

28. US consumption 8% of world population but use 75% of metals on earth
Uses: cars, engines, appliances, weapons, satellites

29. ROCK
A very slow chemical cycle recycles three types of rock found in the earth’s crust:
Sedimentary rock (sandstone, limestone). Formed from sediment of pre-existing rocks that are weathered and eroded
Metamorphic rock (slate, marble, quartzite). Formed when pre-existing rock is subjected to high temperatures or pressure
Igneous rock (granite, pumice, basalt). Formed from cooled magma at or below earth’s surface 29

30. Erosion Transportation Heat, pressure, stress Magma (molten rock)
Weathering
Deposition
Igneous rock Granite, pumice, basalt
Sedimentary rock Sandstone, limestone
Heat, pressure
Cooling
Heat, pressure, stress
Magma (molten rock)
Figure 15.8
Natural capital: the rock cycle is the slowest of the earth’s cyclic processes. The earth’s materials are recycled over millions of years by three processes: melting, erosion, and metamorphism, which produce igneous, sedimentary, and metamorphic rocks. Rock from any of these classes can be converted to rock of either of the other two classes, or can be recycled within its own class. QUESTION: List three ways that the rock cycle benefits your lifestyle.
Melting
Metamorphic rock Slate, marble, gneiss, quartzite
Fig. 15-8, p. 343 30