Tectonics Lesson 3: Divergent Plate Boundaries

Question 1

Define plate boundary

Answer 1

When two tectonic plates meet

Question 2

Define plate margin

Answer 2

The areas adjacent to plate boundaries

Question 3

How many types of plate boundaries are there?

Answer 3

3 types: convergent, divergent, conservative

Question 4

What landforms form at divergent plate boundaries?

Answer 4

Mid-ocean ridges and rift valleys

Question 5

What happens at a divergent plate boundary?

Answer 5

Two plates move apart leading to the formation of new crust

Question 6

How far can mid-ocean ridges extend for?

Answer 6

60,000 km across the ocean floor

Question 7

Example of a mid-ocean ridge

Answer 7

Mid-Atlantic Ridge is a divergent plate boundary

Question 8

Where is the Mid-Atlantic Ridge found?

Answer 8

North American and Eurasian plates

Question 9

How much does the MAR move apart the N. American and Eurasian plates by?

Answer 9

2.5cm each year

Question 10

Which country does the MAR pass thorugh?

Answer 10

Iceland

Question 11

Water temperature at the MAR?

Answer 11

2-4 C

Question 12

Survival time in the water around the MAR?

Answer 12

30-60 mins

Question 13

What type of earthquakes are found at divergent plate boundaries?

Answer 13

Shallow-focus
Occur frequently
Low threat as small and underwater

Question 14

Type of volcanoes at divergent plate boundaries?

Answer 14

Submarine which can grow above sea level to form new islands

Less explosive and more effusive as they are underwater

Question 15

Define effusive

Answer 15

Type of eruption in which lava steadily flows out of a volcano

Question 16

Describe the formation of rift valleys

Answer 16

When the continental plates move apart, the crust stretches and breaks into parallel cracks (faults)
The land between these faults then collapses, forming steep-sided valley

Question 17

Example of a rift valley

Answer 17

East African rift valley

Question 18

What tectonic activity is found at rift valleys?

Answer 18

Only earthquakes of low magnitude and shallow

Question 19

Why are volcanoes not found at rift valleys?

Answer 19

Magma cannot rise rise through the crust as the lithosphere prevents access