The History of Planet Earth

How long ago was the earth formed?

• 4.5 billion years

• 5 million years

• 7 billion years

• 3.7 million years

What process moves the continents across the surface of the Earth?

• mantle movement

• earth quakes

• volcanic activity

• continental drift

The interior of the Earth is still molten, reaching _____________ degrees Celsius in the core.

• 10,000

• 5700

• 4700

• 2000

What created earth's magnetic fields?

• convection currents in the mantle

• convection in the molten inner core moving beneath the mantle

• movement of the molten outer core surrounding the iron inner core

• conduction in the lithosphere moving rare earth minerals

Where did earth's oxygen come from?

• the atmosphere

• photosynthetic cyanobacteria

• chemical breakdown of minerals

• redox reactions

Earth's atmosphere is ___________ % nitrogen and ___________% oxygen.

• 78%, 21%

• 82%, 17%

• 54%, 45%

• 71%, 28%

Continental crust is recycled more often than oceanic crust.

• true

• false

Oceanic crust is thinner than continental crust.

• true

• false

How think is continental crust?

• 30-40 km

• 25-70 km

• 10 km

• 10 miles

How thick is oceanic crust?

• 10 miles

• 25-70 km

• 30-40 km

• 10 km