plate tectonics

Question 1

Lithosphere

Answer 1

the rigid outer part of the earth, consisting of the crust and upper mantle.

Question 2

Asthenosphere

Answer 2

the upper layer of the earth’s mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.

Question 3

Mesosphere

Answer 3

the region of the earth’s atmosphere above the stratosphere and below the thermosphere, between about 30 and 50 miles (50 and 80 km) in altitude.

Question 4

Inner Core

Answer 4

the most inner part of the earth.

Question 5

Outer Core

Answer 5

The outer core of the Earth is a fluid layer about 2,400 km (1,500 mi) thick and composed of mostly iron and nickel that lies above Earth’s solid inner core

Question 6

Seismic Waves

Answer 6

an elastic wave in the earth produced by an earthquake or other means.

Question 7

Oceanic Crust

Answer 7

the relatively thin part of the earth’s crust which underlies the ocean basins. It is geologically young compared with the continental crust and consists of basaltic rock overlain by sediments.

Question 8

Continental Crust

Answer 8

the relatively thick part of the earth’s crust that forms the large landmasses. It is generally older and more complex than the oceanic crust.

Question 9

Density

Answer 9

the degree of compactness of a substance.

Question 10

Alfred Wegener

Answer 10

German meteorologist and geophysicist: originated theory … the 1960s, when new scientific understanding of the structure of the ocean floors … In 1912 Alfred Wegener proposed a radical new idea, called continental drift

Question 11

Continental Drift

Answer 11

the gradual movement of the continents across the earth’s surface through geological time.

Question 12

Convergent Boundary

Answer 12

When continental and oceanic plates collide, the thinner and more dense oceanic plate is overridden by the thicker and less dense continental plate.

Question 13

Divergent Boundary

Answer 13

A tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the Earth’s surface between the two plates. The middle of the Red Sea and the mid-ocean ridge (running the length of the Atlantic Ocean) are divergent plate boundaries.

Question 14

Transform Boundary

Answer 14

are locations where two plates slide past one another. The fracture zone that forms a transform plate boundary is known as a transform fault. Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges.

Question 15

Sea-floor Spreading

Answer 15

the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side.

Question 16

Pangaea

Answer 16

a hypothetical supercontinent that included all current land masses, believed to have been in existence before the continents broke apart during the Triassic and Jurassic Periods.

Question 17

Laurasia

Answer 17

The supercontinent of the Northern Hemisphere that, according to the theory of plate tectonics, broke up into North America, Greenland, Europe, and Asia except for the Indian subcontinent.

Question 18

Gondwana

Answer 18

According to plate tectonic evidence, Gondwana was assembled by continental collisions in the Late Precambrian (about 1 billion to 542 million years ago). Gondwana then collided with North America, Europe, and Siberia to form the supercontinent of Pangea. The breakup of Gondwana occurred in stages.

Question 19

Mesosaurus

Answer 19

Fossils of the seed fern Glossopteris are found across all of the southern continents. These seeds are too heavy to be carried across the ocean by wind. Mesosaurus fossils are found in South America and South Africa. … Wegener used fossil evidence to support his continental drift hypothesis.

Question 20

Glossopteris

Answer 20

Glossopteris is the largest and best-known genus of the extinct order of seed ferns known as Glossopteridales.