Unit 4 Lesson 2

Question 1

Pangaea

Answer 1

The single large landmass that existed 245 million years ago where all the continents were joined

Question 2

Panthalassa

Answer 2

The single large ocean which surrounded Pangaea

Question 3

Continental Drift

Answer 3

In 1912, Alfred Wegener proposed this hypothesis

The continents once formed a single landmass called Pangaea which broke up and drifted apart

Question 4

Evidence to support Continental Drift

Answer 4

Fossils of the same species were found on different sides of the Atlantic Ocean (S America & Africa)

Evidence of mountain ranges and rock formations with similar core in N America and Africa

Same ancient climate conditions on several continents

Evidence that South America and Africa fit together like puzzle pieces

Question 5

Pangaea broke into 2 continents

Answer 5

Laurasia - became North America and Eurasia

Gondwana - broke into South America/Africa
Antarctica/Australia/India

Question 6

Theory of plate tectonics

Answer 6

Explains how and why features in earth’s crust form and how continents move

Question 7

Tectonic Plates

Answer 7

A block of the lithosphere that consists of the crust and the rigid, outermost part of the mantle

The major tectonic plates are: Pacific, North American, Nazca, South American, African, Australian, Eurasian, Indian, and Antarctic plates

Question 8

Sea floor spreading

Answer 8

Molten rock from inside earth rises through the cracks in the ridges, cools, and forms new oceanic crust. The old crust breaks along the mid-point of the ridge and the 2 pieces of crust move apart

So the sea floor slowly spreads apart

Question 9

Ocean trenches

Answer 9

There are huge trenches in the sea floor

Oceanic crust sinks into the asthenosphere. Older crust is destroyed at the same rate new crust is forming

This explains why earth remains the same size

Question 10

Convergent Boundaries

Answer 10

Form where 2 plates collide

3 types of collisions occur:
Continent-continent collision —— forms mountains
Continent-ocean collision. ————oceanic lithosphere subducts because it is denser
Ocean-Ocean collision. ————- the older denser plate subducts

Question 11

Subduction zone

Answer 11

Boundaries where 1 plate sinks beneath another plate

Question 12

Divergent boundary

Answer 12

2 plates move away from each other. Forms mid- ocean ridges

Most are found on the ocean floor

Question 13

Transform Boundaries

Answer 13

A boundary where 2 plates move past each other horizontally

Earthquakes