This chapter discusses Earth's structure and composition, minerals and rocks, and plate tectonics. It describes Earth's layered internal structure consisting of the core, mantle and crust. The core is made of iron and nickel, the mantle is solid but plastic, and the crust composition depends on if it is oceanic or continental. Minerals are the building blocks of rocks and the three main rock types are igneous, sedimentary, and metamorphic which form through volcanism, deposition of sediments, and changes induced by heat and pressure. Plate tectonics explains how the lithosphere is broken into plates that move relative to each other through processes like seafloor spreading and collisions at plate boundaries.

1. Chapter 13: Earth Structure, Earth Materials, and Plate Tectonics Physical Geography Ninth Edition Robert E. Gabler James. F. Petersen L. Michael Trapasso Dorothy Sack

2. Earth Structure, Earth Materials, and Plate Tectonics

3. 13.1 Earth’s Planetary Structure Earth’s radius is 6400 km (4000 miles) Structure and composition deduced by remote sensing Seismic waves Seismograph P (primary) waves S (secondary) waves

4. 13.1 Earth’s Planetary Structure Seismic Waves Earth’s Internal Structure (crust, mantle, outer core, inner core)

5. 13.1 Earth’s Planetary Structure Earth’s Core 1/3 of Earth’s mass Enormous pressure Iron and nickel Inner core: Solid Outer core: molten lava

6. 13.1 Earth’s Planetary Structure Earth’s Mantle Largest of interior zones Solid rocky material Less dense than core Plastic solid Outermost layer behaves like an elastic solid (rigid) Lithosphere (upper most mantle and crust)

7. 13.1 Earth’s Planetary Structure Earth’s Mantle Asthenosphere: upper mantle Tectonic forces come from movement of Asthenosphere Moho discontinuity

8. 13.1 Earth’s Planetary Structure Earth’s Crust 1% of Earth’s mass Exterior of lithosphere Density Oceanic crust (basaltic) Continental crust (granitic)

9. 13.2 Minerals and Rocks Minerals Building blocks of rocks Inorganic Naturally occurring Rock Aggregate (collection) of minerals or an aggregate of the same mineral Most Common Elements

10. 13.2 Minerals and Rocks Minerals Distinct and recognizable characteristics Hardness Luster Cleavage Tendency to fracture Specific gravity Geometric shapes Chemical Composition Silicon, oxygen, and carbon Silicates

11. 13.2 Minerals and Rocks Rocks Building material Weathered and eroded Bedrock Regolith Outcrop 3 Major Categories of Rocks Igneous Sedimentary Metamorphic

12. 13.2 Minerals and Rocks Igneous Rocks Molten rock material cools and solidifies Magma (below surface) Lava (at surface) 2 Major categories of Igneous: Extrusive Intrusive

13. 13.2 Minerals and Rocks Extrusive Extrusive igneous rock (volcanic rock): solidifies at surface Pyroclastics (fine fragments) Intrusive Intrusive igneous rock: molten magma solidifies (freezes) Also called plutonic rock

14. 13.2 Minerals and Rocks Chemical Composition of Igneous Felsic, Mafic, Dionite, Andesite Extrusive: Basalt, Andesite, Rhyolite Intrusive: Gabbro, Diorite, Granite

15. 13.2 Minerals and Rocks Geometric patterns Columnar joints Devil’s Postpile, CA and Devil's Tower, WY

16. 13.2 Minerals and Rocks Sedimentary Rocks Accumulated sediment Unconsolidated, minerals that have been eroded, transported and deposited Clasts Clastic

17. 13.2 Minerals and Rocks Sedimentary Rocks Organic sedimentary Coal Limestone Chemical sedimentary rocks Dolomite

18. 13.2 Minerals and Rocks Sedimentary Rocks Stratification Strata Bedding planes Unconformity Cross bedding Fins

19. 13.2 Minerals and Rocks Metamorphic Rocks Changed form due to enormous heat and pressure Harder Foliation Two major Types: Foliated (presence of platy or wavy surfaces) Nonfoliated (absence of platy or wavy surfaces)

20. 13.2 Minerals and Rocks Metamorphic Rocks Schist Gneiss Marble

21. 13.2 Minerals and Rocks Rock Cycle Q: What conditions are necessary to change igneous to metamorphic?

22. 13.3 Continents in Motion: The Search for a Unifying Theory Continental Drift Plate Tectonics Catastrophism Uniformitarian

23. 13.3 Continents in Motion: The Search for a Unifying Theory Continental Drift Idea that continents and other landmasses have shifted Wegener Pangaea Gondwana Laurasia Q: How has continental movement affected the climates of landmasses?

24. 13.3 Continents in Motion: The Search for a Unifying Theory Supporting Evidence for Continental Drift Radioactive dating Paleomagnetism Reconstructed locations of continents 200 mya continents joined together Similar fossil reptiles and plants

25. 13.3 Continents in Motion: The Search for a Unifying Theory Supporting Evidence for Continental Drift Glaciation Rocks of ancient mountain ranges Paleogeographic reconstruction

26. 13.4 Plate Tectonics Plate Tectonics Modern theory to explain movement of continents Lithosphere is broken Plates move in distinct and discrete units Plates Diverge, converge, or move laterally 7 major plates

27. 13.4 Plate Tectonics Plate Tectonics Q: Does every lithospheric plate include a continent?

28. 13.3 Continents in Motion: The Search for a Unifying Theory Seafloor Spreading and Convection Currents Undersea mapping Mid-ocean ridges Parallel bands of matching magnetic patterns Rocks on ocean floor very young! Oldest rocks lie next to continents

29. 13.3 Continents in Motion: The Search for a Unifying Theory Seafloor Spreading and Convection Currents

30. 13.3 Continents in Motion: The Search for a Unifying Theory Seafloor Spreading Polarity reversals

31. 13.3 Continents in Motion: The Search for a Unifying Theory Seafloor Spreading Convection Q: Why is plate tectonics a better name than continental drift for the lateral movement of Earth’s solid outer shell?

32. 13.3 Continents in Motion: The Search for a Unifying Theory Tectonic Plate Movement Pulling apart, pushing together, or sliding alongside

33. 13.3 Continents in Motion: The Search for a Unifying Theory Plate Divergence (pulling apart) Seafloor spreading Shallow earthquakes Creates new ridges Most occur near oceanic ridges (e.g. Iceland)

34. 13.3 Continents in Motion: The Search for a Unifying Theory Plate Divergence (pulling apart) Rift Valley, Africa

35. 13.3 Continents in Motion: The Search for a Unifying Theory Plate Convergence (pushing together) Denser plate forced under lighter plate This is known as subduction Examples: Nazca Plate subducts beneath South America Japan

36. 13.3 Continents in Motion: The Search for a Unifying Theory Plate Convergence Deep ocean trenches Mountain ranges (ocean-continent) Cascades Andes Islands (ocean-ocean) Aleutians Kuriles

37. 13.3 Continents in Motion: The Search for a Unifying Theory Plate Convergence Larger Landmasses (continent-continent) Continental Collision Himalayas Tibetan Plateau

38. 13.3 Continents in Motion: The Search for a Unifying Theory Transform Movement Plates slide pass each other Examples San Andreas Fault, CA Ocean plates

39. 13.3 Continents in Motion: The Search for a Unifying Theory Hot Spots Almost stationary molten masses that rise to surface Hawaiian Islands

40. 13.4 Growth of Continents Origin of continents still debated Continental shields (ancient crystalline rock) Example: Canadian Shield Accretion Microplate terranes

41. 13.4 Growth of Continents

42. 13.5 Paleogeography Paleogeography Reconstruct the past environment of a geographical region based on geologic and climate evidence Earth History Eras Periods Epochs

43. 13.5 Paleogeography Q: How has the environment at the location where you live changes through geologic time?

44. Physical Geography End of Chapter 13: Earth Structure, Earth Materials, and Plate Tectonics