Chapter 1: Plate Tectonics

pg 8-15

How many continents are there in the world? Name them from largest to smallest.

7, Asia, Africa, North America, South America, Antarctica, Europe, Australia

What are the four main oceans in the world? Name them from largest to smallest.

The Pacific Ocean, The Atlantic Ocean, The Indian Ocean, The Artic Ocean

What are the seven main tectonic plates? Name them from largest to smallest.

Pacific, North American, Eurasian, African, Antarctic, Indo-Australian, South American

What are the four layers of the earth?

Crust, mantle, outer core, inner core

What did Alfred Wegener discover in 1912.

Pangaea (a supercontinent) and continental drift.

What did Harry Hess discover?

Sea floor spreading

What are the two types of crusts?

Oceanic and continental

Crust

The outer layer of the Earth that we live on. It is approximately 6-70km thick. It is divided into different plates and is made up of land and ocean. The crust contains solid rock.

Mantle

Made up of hot molten rock called magma that is approximately 4,000°C. The mantle makes up 85% of the earth.

Outer core

Made up of liquid iron and nickel. Its movement gives Earth its magnetic field.

Inner core

Made up of solid iron and nickel.

Continental drift

The theory that the Earth’s continents have moved slowly to their current positions due to convection currents. It is believed that the world used to be one big land mass known as Pangaea, which broke down into Laurasia and Gondwanaland, eventually breaking up into the current seven continents.

Sea floor spreading

The geological process at constructive boundaries where new crust is formed at mid-ocean ridges and pushes older crust away from the ridge.

Convection currents

Heat-driven cycles of rising and sinking magma in the mantle causing plates to move.

Pangaea

A supercontinent that is believed to have existed around 200 million years ago. It broke down into Laurasia and Gondwanaland, eventually breaking down into the current 7 continents due to continental drift and convection currents.

Plates

Massive, irregularly shaped slabs of rock that make up the Earth’s crust. They can be continental of oceanic.

Lava

Hot, molten rock that erupted from a volcano or fissure.

Plate boundary

The zone where two plates meet.

Oceanic plate

A plate that primarily carries ocean. They are around 6-10km thick. Although they are thinner than continental plates, they are denser, causing them to be heavier. Eg. Pacific Plate

Continental plate

A plate that primarily carries land. They are 40-70km thick. Although they are thicker than oceanic plates, they are less dense, causing them to be lighter. Eg. Eurasian Plate

Subduction

When an oceanic plate is dragged down and recycled into the mantle as it collides with a continental plate. Subduction causes trenches, earthquakes and volcanoes. Eg. Mariana Trench

What features do constructive boundaries create.

Earthquakes, volcanoes, mid-ocean ridges Eg. Mid-Atlantic Ridge

What features do destructive boundaries (continental) create?

Fold mountains, earthquakes Eg. Himalayas

What features do destructive boundaries (oceanic-continental) create?

Deep trenches, earthquakes, volcanic mountains Eg. Mariana Trench

What features do transform boundaries create?

Earthqukes Eg. 1994 Northbridge quake