The Layers of the Earth and Its Composition

Question 1

the thinnest and outermost layer of Earth

Chemical Layer

Answer 1

Crust

Question 2

older and more buoyant

Crust

Answer 2

Continental Crust

Question 3

average of thickness of continental crust

Answer 3

35 km

70 km in mountainous regions

Question 4

average composition and density of continental crust

Answer 4

Granite, 2.7 g/cm^3

Question 5

younger and denser part of crust

Answer 5

Oceanic Crust

Question 6

average thickness of oceanic crust

Answer 6

7 km

Question 7

average composition and density of oceanic crust

Answer 7

basalt, 3.0 g/cm^3

Question 8

crust-mantle boundary

Answer 8

Mohorovicic Discontinuity

Question 9

makes up around 80% of Earth’s volume

Chemical Layer; has a depth of 2,900 km

Answer 9

Mantle

Question 10

boundary that divides the upper mantle from the lower mantle

Answer 10

Repetti Discontinuity

Question 11

mantle-core boundary

Answer 11

Gutenberg Discontinuity

Question 12

comprises a Fe-Ni alloy

Chemical Layer; Fe = iron, Ni = nickel

Answer 12

Core

Question 13

density of core

Answer 13

11 g/cm^3

Question 14

thick and brittle layer; crust and upper portion of upper mantle

Physical Layer

Answer 14

Lithosphere

Greek lithos - “stone”

Question 15

average thickness of lithosphere

Answer 15

100 km

300 km in thickest portions of continents

Question 16

mechanically weak layer; lower portion of upper mantle

Physical Layer; responsible for plate tectonics

Answer 16

Asthenosphere

Greek asthenes - “weak”

Question 17

Mg- and Fe- rich rock found in the upper mantle

Answer 17

Peridotite

Question 18

the lower mantle; 2,900 km in depth

Physical Layer

Answer 18

Mesosphere

Greek mesos - “middle”

Question 19

silicate rock that makes up the mesosphere

Answer 19

Perovskite