Chapter 1 Gateway 1 Tectonic Plates

Question 1

What are the characteristics of the Earth’s core?
(thickness and temperature)

Answer 1

The inner core is a solid layer 1400km thick
The outer core is a liquid layer 2100lm thick
3000°C to 5000°C

Question 2

What are the characteristics of the Earth’s mantle?
(thickness and temperature)

Answer 2

2900km thick
800°C to 3000°C

Question 3

What are the characteristics of the Oceanic crust?
(location, thickness, and type and age of rock)

Answer 3

Located beneath deep oceans
5km to 8km
Consists mainly of basalt
Rock of less than 200 millions years old

Question 4

What are the characteristics of the Continental crust?
(location, thickness, and type and age of rock)

Answer 4

Beneath continents and shallow seas near them
35km to 70km
Consists of lighter rock, like granite
From very recent to nearly 4 billions years old

Question 5

Explain convection currents (4 parts)

Answer 5

-Nearer the core, mantle material is heated up, expand, rise and spread out beneath the plate
-Plates dragged along and move away from each other
-As the hot mantle cools, it sinks and pulls the plates toward one another
-Nearer the core, mantle heats up again and cycle continues

Question 6

Explain slab-pull force

Answer 6

The dense, sinking oceanic plate at subduction zone pulls the rest of the plate behind it. The subducting plate drives the downward-moving portion of convection currents. The mantle material which is found away from where the plates subduct drives the rising portion of convection currents

Question 7

Describe OC-OC divergence
(T M R P L)

Answer 7

T: When two oceanic plates
M: diverge
R: tensional forces cause fractures to form at the plate boundary
P: Magma rises at the zone of divergence through cracks to create a ridge of new ocean floor known as the Mid-oceanic ridge. This process is known as seafloor spreading.
At various points along the mid-oceanic ridge, magma builds up, cools and solidifies to form under sea volcanoes. As these volcanoes continue to grow, they eventually grow above sea level to form volcanic islands
(eg. North American and Eurasian Plates diverge, forms Mid-Atlantic Ridge, volcanic islands Azores)