Geology Test 2

Question 1

What is a seamount?

Answer 1

A volcano that forms on ocean floor

Question 2

What is a continental shelf?

Answer 2

A gently sloping, submerged surface extending from the shoreline toward the deep ocean

Question 3

What meteorologist proposed pangea?

Answer 3

Alfred Wegner

Question 4

What was some of the evidence for Pangea?

Answer 4

• Fossils matching across the seas
• Continents fit together like jigsaw puzzles
• ## Rock types match on the edges of continents

Question 5

Why did people object Wegner’s theory?

Answer 5

He had no mechanism for continental drift

Question 6

What is the theory of plate tectonics?

Answer 6

Earth’s outer shell is made of fragmented, individual plates that interact in various ways & produce volcanoes and earthquakes

Question 7

Whats the relationship between asthenosphere and lithosphere?

Answer 7

A rigid lithosphere overlies the weak asthenosphere

Question 8

List all the plates

Answer 8

Major: North American, South American, Pacific, African, Eurasian, Australian-Indian, and Antarctic plate

Intermediate: North American, South American, Pacific, African, Eurasian, Australian-Indian, and Antarctic plate

Question 9

Describe divergent plates

Answer 9

Where plates move apart, creating partial upwelling of material from the mantle and new seafloor. Located at oceanic ridges

Question 10

Describe convergent plates

Answer 10

Where plates move together, resulting in either oceanic lithosphere descending beneath an overriding plate, then getting reabsorbed into the mantle, or in the collision of two continental blocks to create a mountain belt

Question 11

Describe transform plates

Answer 11

Where two plates grind past each other without the production or destruction of lithosphere, least common

Question 12

What is a rift valley?

Answer 12

A long trough that shows where divergence is taking place, there is one in Ireland

Question 13

Describe continental rifting

Answer 13

Tensional movements that pull the lithosphere apart, the mantle upwells and makes the lith thin. The stretching makes the crust break into pieces that sink. That is the continental rift. Continued spreading creates a linear sea then a deep ocean basin.

Question 14

What is a subduction zone?

Answer 14

Where the lithosphere subducts into the mantle, at convergent plates

Question 15

The younger the seafloor, the more/less dense?

Answer 15

Young seafloor is less dense

Question 16

what happens at an oceanic-continental convergence

Answer 16

They collide, oceanic subducts bringing water down with it, starting partial melting which produces magma. the magma rises and becomes a chain of erupting volcanos

Question 17

what happens at an oceanic-oceanic convergence?

Answer 17

The older, denser of the two will subduct, Melting occurs and the magma rises and makes a volcanic island arc

Question 18

what happens at a continental-continental convergence?

Answer 18

the two sides crunch into each other and huuuge mountains like the himalayas

Question 19

What is some evidence that the plates are spreading?

Answer 19

They drilled into the ocean floor to check its age and depth of it, and near the rift the floor was thin and away from it was thick. AND volcanic chains like Hawaii show that volcanos are made in chains. Paleomagnetism.