Chapter 12 - Earth History, Earth Interior

Question 1

crust

Answer 1

rigid outermost layer of Earth

Question 2

volcano

Answer 2

mountain or hill formed by eruptions of lava and rock fragments

Question 3

cyanobacteria

Answer 3

photosynthetic bacteria

Question 4

unifortarianism

Answer 4

the principle that the same gradual and nearly imperceptible processes operating now have operated in the past

Question 5

relative age

Answer 5

compares the age of one object or event with the age of another, without specifying how old either object is

Question 6

absolute age

Answer 6

age of an object specified in years before the present

Question 7

superposition principle

Answer 7

states that in a sequence of rock layers, the oldest rocks are at the bottom and the younger rocks are on top

Question 8

radiometric dating

Answer 8

a method of calculating absolute age that involves using unstable atoms in materials to assign ages to those materials

Question 9

seismic waves

Answer 9

energy released by earthquakes that travels through Earth’s interior

Question 10

earthquake

Answer 10

sudden shaking of the ground caused by the movement of Earth’s crust

Question 11

inner core

Answer 11

portions of the Earth which extends from Earth’s center to abut 5,150 km (3,200 mi) below Earth’s surface

Question 12

outer core

Answer 12

layer composed of liquid alloys of iron and nickel, extending about 2,900 km (1,800 mi) below Earth’s surface

Question 13

lower mantle

Answer 13

layer of Earth composted of heated and slowly deforming solid rock that lies between the base of the crust and the outer core

Question 14

asthenosphere

Answer 14

layer of the mantle found between depths of 100 km and 200 km (62 mi and 124 mi) that is weaker and softer than the layer beneath it

Question 15

lithosphere

Answer 15

layer of Earth that is relatively strong and consists of Earth’s rigid crust and the rigid lithospheric mantle beneath it, extending to a depth of about 100 km (62 mi)

Question 16

continental crust

Answer 16

makes up the continents

Question 17

granite

Answer 17

a silica-rich rock made up of coarse grains

Question 18

oceanic crust

Answer 18

lies beneath the ocean and is composed mainly of basalt

Question 19

basalt

Answer 19

a dark, heavy, fine-grained volcanic rock

Question 20

lava

Answer 20

magma that spills onto the surface of Earth’s crust

Question 21

moho

Answer 21

also called mohorovičić discontinuity, this is the boundary that separates the crust from the lithospheric mantle below

Question 22

plate tectonics

Answer 22

a theory addressing the origin, movement, and recycling of lithospheric plates and the landforms that result