United States History Student Edition

Migration Routes Throughout Earth’s history, the planet’s climate has changed. Several periods of extreme cold, known as ice ages, have occurred. The most recent of these ice ages began roughly 100,000 years ago and ended about 10,000 years ago, or in about 8000 B.C.E. During this time, a large share of Earth’s water formed huge sheets of ice, or glaciers. The glaciers held so much water that ocean levels were lowered. The lower sea level exposed a strip of land—a “land bridge”—connecting Asia and North America between what are now Siberia and Alaska. Scientists refer to the land bridge as Beringia.

About 15,000 years ago, temperatures started to rise, leading to the end of the last ice age. Eventually, glaciers melted, causing the oceans to rise, and Beringia vanished beneath the Bering Strait. A strait is a narrow body of water that connects two larger ones. For some time, many scientists thought of Beringia as a short-lived land bridge that enabled people to migrate from Asia to North America. In this theory, those migrants were the ancestors of all Native Americans; they continued to migrate and spread out across all of North and South America. Recently, some scientists have come to believe that Beringia was not just used for travel, but that it was inhabited for thousands of years.

strait a narrow passage of water between two larger bodies of water

Routes to the Americas The last ice age lowered ocean levels all over the world. Over thousands of years, prehistoric people migrated to and then throughout the Americas.

ARCTIC OCEAN

A

R

C

Present-day land area Additional land area during last ice age

T I

C

ASIA

60°N

C

I R

Beaufort Sea

C

L E

u t e s

L a n d r o

60°N

Baff in Bay

120°E

30°W

Bering Sea

NORTH AMERICA

ATLANTIC OCEAN

L a n d

t e

o u

S e a r

r o u t

e s

30°N

30°N

S e

a r

o

u

t

e

T R O P I C O

F C A N C E R

N

150°E

PACI FIC OCEAN

0

2000 miles

60°W

W

E

SOUTH AMERICA

2000 kilometers

0

S

Azimuthal Equidistant projection

180°

150°W

120°W

90°W

EQUATOR

GEOGRAPHY CONNECTION 1. Spatial Thinking Based on this map, how did prehistoric people get to North America from Asia? 2. Patterns and Movement Why do you think prehistoric people moved from one place in the Americas to another?

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