37. Differentiate Oceanic and Continental
Crust in four ways.
Characteristic Oceanic
Composition Basalt
Continental
Granite
Thickness 20-50 km 8 km
Density Higher Lower
Age Newer Older
38. Differentiate between the different layers of the Earth w.r.t. density, temperature, thickness and composition.
Thickness
Crust
Temp. Composition Density
5-50 solid rock Lowest km
Mantle
Lithosphere 100 km
Solid Rock
Asthenosphere 300 km
Mesosphere 2900 km
Fluid Rock
Solid Rock
Outer Core 2300 Liquid Fe &

km Ni
Inner Core 1200 km
Solid Fe &
Ni
Highest
39. What is the Moho? It is the boundary between the crust and mantle.
40. Why can’t we visit the center of the
Earth, and how do we know all of this “stuff” without having been there? The center of the Earth is too hot and too high of a pressure. We know about the inside of the
Earth because of Seismological Studies.
41. Why is it so hot in the middle of the
Earth? Left over heat from the formation of the solar system and natural radioactive decay

42. What layers (exactly) of the Earth comprise the lithosphere? All of the crust and the uppermost solid part of the mantle.
43. What makes some parts of the Earth solid even though they’re at higher temperatures than the neighboring layers?
Intense Pressure allows materials at higher temperatures to exist as a solid.
44. Draw a picture of a convection current and label what is happening to the molecules as they rise and fall. As the mantle is heated by the core, the molecules move apart and it becomes less dense. Less dense mantle rises.
As the mantle nears the crust, it cools down, molecules get closer together, the mantle becomes more dense and it sinks to start the cycle all over again.
45. Draw a picture of all three types of plate boundaries. Divergent: spreading apart,

Convergent: coming together, and
Transform: sliding past one another.
46. What four pieces of evidence allowed scientists to embrace the Theory of Plate Tectonics? a. Continents fit together like puzzle pieces b. Climate change on the continent c. Matching Rock Formations d. Fossil Evidence
47. What evidence exists at the Mid-Atlantic Ridge to support sea-floor spreading. Magnetic Reversals
48. Match the following features with the plate boundaries that create them.
Mountain Convergent Cont. to Cont.
Volcano Convergent Cont. to Oceanic
Deep Sea Trenches Convergent Oceanic to Oceanic
Rift Valley Divergent Cont. to Cont.
Earthquake Transform
Mid-Ocean Ridge Divergent Oceanic to Oceanic
Island Arcs Convergent Oceanic to Oceanic

49. What causes continents to move? Convection currents in the asthenosphere