Chapter 3

Question 1

Earths Interior Structure (Compositional)

Answer 1

Crust (felsic (continental crust, lower density)
Mantle, upper and lower (ultramafic rock)
core (Fe-Ni alloy, aka ___ nickel alloy). made of outer and inner core

Question 2

Earths Structure (Strength/Behavior)

Answer 2

Inner/outer core (inner is solid, outer is liquid).

Asthenosphere (weak since it becomes hotter and hotter, allows plates to move),

lithosphere (crust and uppermost mantle aka tectonic plates).

Question 3

Geologic Evidence: Surface Exposures

Answer 3

Exposure at the surface,

Question 4

Geologic Evidence: Meteorites

Answer 4

Consist of Iron and Stone. There are two types, and combinations of the two

Question 5

Geologic Evidence: Seismologic Evidence

Answer 5

seismic wave reflection and refraction (changes direction of seismic ray), lowest velocity at the top. Consists of seismic waves (source in center) creating a seismic ray path

Question 6

MOHO

Answer 6

crust/mantle boundary (where crust and mantle meet, slower and less dense at crust). Increase in seismic velocities.

Question 7

Mantle Convection

Answer 7

Convection:
Hot, hot, less dense mantle rises. Cools at base of lithosphere.

Cold, dense mantle sinks. Occurs in continuous cycle. Heat loss by radiation cools the surface. Occurs at asthenosphere (upper layer of earth’s mantle)

Question 8

Earths Magnetic Field

Answer 8

generated by connection of liquid iron in Outer Core.

Magnetic poles also reverse periodically in geologic time (not aligned with Antarctica and the Arctic, have been completely reversed before, cause of reversals is unknown, humans haven’t lived through a reversal of the poles).

Magnetic north pole, and magnetic south pole, and inclination (causes compass needle to tilt up or down).

Question 9

Continental Crust

Answer 9

thicker, felsic (has minerals that are richer in silica) which makes it less dense (floats higher)

Question 10

Ocean Crust

Answer 10

thinner, mafic (more iron and magnesium than silica), higher density (floats lower)

Question 11

Crust

Answer 11

Solid and silicate

Question 12

Mantle

Answer 12

ultra-mafic (more iron and magnesium than mafic rocks, less silica). Solid and silicate

Question 13

Peridotite

Answer 13

rocks higher in the mantle, contains much olivine and pyroxene.

Question 14

Eclogite

Answer 14

rocks formed lower in the mantle from extreme pressure, contains garnets

Question 15

Lithosphere

Answer 15

contains both crust and mantle (uppermost mantle layer stuck to the underside of the crust), tectonic plates are fragments of lithosphere

Question 16

Asthenosphere

Answer 16

beneath lithosphere, consists of melted rock, weaker (than lithosphere). Plate tectonics are made possible due to the weakness of the asthenosphere. Low velocity zone within the upper mantle.