1. The Dynamic Planet Current Weather Geologic Time and Change
Earth Materials
The Rock Cycle
For Next Class: Read Chapter 11 (pp )

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7. Geologic Time and Change
Figure 11.2

8. Relative Time and Superposition
Principle of superposition
Youngest bed is at the top of a rock formation and oldest at the base.
Unless they have been disturbed

9. Relative Time and Superposition
Figure 11.3

10. Earth’s Structure
Figure 11.6

11. Earth’s Interior
Scientists have drilled down to 12.2 km (7.6 mi).
Knowledge of internal structure is from indirect evidence.
Seismic waves from earthquakes pass through different layers differently.
Seismic waves speed up in cold, rigid regions and slow down in hotter, more plastic or fluid regions.
Core is hottest, surface is coolest.

12. Seismic Waves
Figure 11.5

13. Earth’s Structure Core at center, mantle in middle, crust at surface
Core makes up 1/3 Earth’s mass, 1/6 volume.
Inner core is solid iron at 6000°C (10,800°F).
Outer core is molten, liquid iron.
Boundary between core and mantle is the Gutenberg discontinuity.
Mantle makes up 80% of Earth’s volume.
Lower mantle is hot enough for rocks to flow slowly.
Boundary between mantle and crust is the Mohorovičić (Moho) discontinuity.

14. Earth’s Structure Crust is outer layer.
Eight elements make up 98% of crust by weight.
Almost half is oxygen (46%).
Continental crust lower in density than oceanic crust
Continental crust made of silica and aluminum (sial)
Oceanic crust made of silica and magnesium (sima)

15. Earth’s Structure
Lithosphere is the rocky layer made up of the crust and uppermost mantle.
Asthenosphere is a plastic layer below the crust.
Convection currents in the asthenosphere drive plate tectonics.

16. Earth’s Structure
Figure 11.6

17. Distance Core to Crust
Figure 11.7

18. Elements in Earth’s Crust
Figure 11.8

19. Earth’s Magnetic Field
Magnetic field is generated by the fluid outer core.
Magnetic north and south poles move.
North magnetic pole is moving 60 km/year!
Magnetic poles are not the same as the geographic poles.
Earth’s magnetic field reverses from time to time.
Four reversals in last nine million years
Provides important evidence of plate tectonics

20. Earth’s Magnetic Field
Figure 11.9

21. In-Class Assignment
What are the differences between rocks and minerals?
What are the three basic rock types?

22. Earth’s Materials and the Rock Cycle
A mineral is an inorganic (nonliving) natural compound having a specific chemical formula and possessing a crystalline structure.
A rock is an assemblage of minerals bound together, or a mass of a single mineral, or undifferentiated material, or even solid organic material (such as coal).
Three basic rock types
Igneous (was molten)
Sedimentary (from sediment)
Metamorphic (changed by heat/pressure)

23. Igneous Rock Cools and solidifies from magma
Magma at the surface is lava.
Intrusive igneous rock cools below the surface.
Cools slowly
Smaller or no crystals
Extrusive igneous rock cools on the surface.
Cools quickly

24. Intrusive Granite and Extrusive Basalt
Figure 11.11

26. Multiple Plutons Form a Batholith
Figure 11.12

27. Igneous Intrusions and Landforms
Figure 11.13

28. Sedimentary Rock
Weathering disintegrates and dissolves rock into grains or fragment called clasts.
Erosion by gravity, water, wind, and ice carries clasts.
Sedimentary rocks are classified into clastic and chemical.
Clastic sedimentary rock forms by compaction or cementation.
Chemical sedimentary rock forms by chemical precipitation of minerals.

29. Sedimentary Rocks: Sandstone and Limestone
Figure 11.14

31. Metamorphic Rock
Igneous or sedimentary rock may be transformed to metamorphic rock through high pressure and/or heating.
Contact metamorphism occurs in the upper crust when rising magma “cooks” adjacent rock.
Regional metamorphism occurs deep in the lithosphere.

32. Metamorphic Processes
Figure 11.17

34. The Rock Cycle
Figure 11.18