The Solar System

Mike Seeds

National Geophysical Data Center

HawaiiHawaii

Not long ago, Earth’s

continents came

together to form one

continent.

Pangaea broke

into a northern

and a southern

continent.

Notice India moving

north toward Asia.

The continents are

still drifting on the

“plastic” upper

mantle.

Yellow lines on
this globe mark
plate boundaries. Red
dots mark earthquakes since 1980. Earthquakes
within the plate, such as those at Hawaii, are
related to volcanism over hot spots in the mantle.

4 3 2 1 Now

?

Billions of years ago

Formation of Grand Canyon

Formation of Earth Age of dinosaurs

Heavy bombardment Breakup of Pangaea

Oldest fossil life First animals emerge on land

4.6

3 Plate tectonics pushes up

mountain ranges and causes

bulges in the crust, and water

erosion wears the rock away. The

Colorado River began cutting the

Grand Canyon only about 10 million

years ago when the Colorado

plateau warped upward under the

pressure of moving plates. That

sounds like a long time ago, but it is

only 0.01 billion years. A mile down,

at the bottom of the canyon, lie

rocks 0.57 billion years old, the

roots of an earlier mountain range

that stood as high as the

Himalayas. It was pushed up, worn

away to nothing, and covered with

sediment long ago. Many of the

geological features we know on

Earth have been produced by

relatively recent events.

2 The floor of the Atlantic Ocean is not being subducted. It is locked

to the continents and is pushing North and South America away from

Europe and Africa at about 3 cm per year, a motion called continental drift. Radio astronomers can measure this

motion by timing and comparing radio signals from pulsars using European and American radio telescopes.

Roughly 200 million years ago, North and South America were joined to Europe and Africa. Evidence of that lies

in similar fossils and similar rocks and minerals found in the matching parts of the continents. Notice how North

and South America fit against Europe and Africa like a puzzle.

1d The floor of the Pacific Ocean is sliding into subduction zones in many places around its perimeter. This pushes up mountains

such as the Andes and triggers earthquakes and active volcanism all
around the Pacific in what is called the Ring of Fire. In places such as
southern California, the plates slide past each other, causing frequent
earthquakes.

Gondw

anala

n

Lauras

ia

200 million years ago

Continental Drift

Pa

nga

ea

Today

65 million years ago

135 million years ago