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20°N140°E130°E120°E110°E100°E

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Malay Peninsula

S u ma t r a

Java

Borneo

New GuineaBali

Sulawesi(Celebes)

PHILIPPINEISLANDS

PACIFIC

OCEAN

INDIANOCEAN

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S

EW

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0 600 Kilometers

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300

Land areas during thelast glacial period about18,000 years ago

Current extent ofland areas

NGWG_GEO_U11_C21_S1.1_M013NGM66 GA83 Historical Land BridgesFirst Proof02/15/11

Name Class Date

© National Geographic Learning, Cengage Learning

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ACTIVE HISTORY U

NIT 1 Chapter 1

Lesson 1.4

Compare Past and Present Land AreasRead the passage below and study the map, which uses shading to show land areas in Southeast Asia during the last glacial period. Then answer the questions.

Southeast Asia: Past and PresentGlacial Period About 20,000 years ago, much of Earth’s water was frozen. Glaciers more than a mile thick covered parts of North America and northern Europe. Because so much water was frozen, sea levels around the world were about 400 feet lower than they are today. Large areas of land were above the water level, which led to the creation of dry land bridges. The first humans in North America crossed from Asia on such a land bridge.

Land Bridges in Southeast Asia Glaciers did not cover Southeast Asia during this period, but the falling sea levels created many land bridges there as well. For example, the Malay Peninsula and several of the islands of Indonesia were once connected by land. Plants, animals, and people could migrate across these land bridges.

Rising Sea Levels As the last glacial period ended about 18,000 years ago, the melting of ice resulted in slowly rising sea levels. About 6,000 years ago, the levels began to stop at present-day levels. Recently, however, sea levels have been rising even more quickly.

1. Compare Maps Examine the map shown at right. Which islands of modern Indonesia were linked with mainland Asia during the last glacial period? What major islands were not linked? What might explain this situation?

2. Make Inferences What changes could have taken place in this region while the land areas were connected?

3. Make Predictions Modern sea levels are rising. If they continue to rise quickly, what might happen to island countries?

SOUTHEAST ASIA: PAST ANd PRESENT

Chapter 1 Lesson 1.4