Preview - Winds of Change

Winds of Change

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Winds of Change (50:00)

Item# 8508
©1998

Plate tectonics is the movement of the super-continents as they split apart. They also collided and joined back together again. When they did, mountains, such as the Himalayas and the Tibetan plateau, were formed. These collisions also disrupted prevailing weather patterns and established new ones. See how 7 million years ago, as a result of India colliding with the Asian land mass, Africa became drier, and our ancestors were driven out of the forests onto the savannah. In Asia, this collision resulted in monsoon rains that became linked to the tides in the western Pacific. This comprehensive explanation details how any oscillation in this pattern can result in typhoons and crop failures from California to Kenya. A BBC Production. (50 minutes)

Segments in this Video - (11)

1. Mountains and Earthquakes (02:47)

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Scientists have only recently begun to understand how and why the world's great mountain ranges formed. A geologist monitors earthquakes and conducts research in the mountains of Greece to support a radical theory of how mountains are made.

2. Mountains, Earthquakes, and Plate Tectonics (02:54)

Scientists monitor earthquakes using a global network of seismometers originally installed to detect Soviet underground nuclear weapons tests. Discovery of a global pattern of earthquakes confirmed the theory of plate tectonics.

3. Earthquakes Build the Himalayas (04:58)

Scientists have searched for clues linking Himalayan earthquakes to the mountains since the 1960s. Recently discovered evidence shows earthquakes in the region cause the land to rise at a fast rate and indicates the Himalayas are still growing.

4. Colliding Continents Build Mountains (05:39)

Scientists search for evidence of the fundamental forces at work creating the Himalayan Mountain Range. The Himalayas are made of rocks that at one time were part of the ocean floor; plate tectonics explain that as continents collide they push up mountain ranges.

5. Mountain Building Forces in the Himalayas (05:10)

With knowledge of mountain building events that occur deep within Earth's crust, scientists search the peaks around Mount Everest to determine when the Himalayas became so high. Dating granite samples indicates that mountain building forces peaked in the Himalayas 20 million years ago.

6. Fluid Theory of Mountains: The Tibetan Plateau (05:21)

Plate tectonics does not adequately explain the formation of the Tibetan Plateau. A scientist theorizes the fluidity of rocks below Earth's crust might provide an explanation and applies the laws of fluid motion to develop a model supporting his theory.

7. Fluid Theory of Mountains: The Mountains of Greece (05:17)

A theory linking the fluidity of rock below Earth's crust to formation of the Tibetan Plateau also predicts mountains will flow away when the force pushing them up stops. Normal faults and measurements show that mountains in Greece appear to be flattening out in this manner.

8. Fluid Theory of Mountains: The Paradox of Tibet Sinking (07:05)

Though India is still moving into Asia and pushing up the Himalaya Mountains, normal faults and climate evidence suggest that Tibet is sinking. A geologist theorizes that 10 million years ago Tibet suddenly increased in height to a point that could not be supported and so began to sink.

9. Fluid Theory of Mountains: Explaining the Paradox of Tibet Sinking (04:34)

Plant structures strongly reflect the climates in which they grow. Fossil leaves from the Tibetan Plateau provide evidence that Tibet suddenly rose 10 million years ago and then began to fall; the evidence supports the fluid theory of mountains.

10. From Tibet to Death Valley (03:56)

The same geological processes that are causing Tibet to sink occurred at California's Death Valley long ago. In a few million years, parts of Tibet likely will become, like Death Valley, one of the lowest places on Earth.

11. Mountains Ebb and Flow (01:21)

Discoveries over the past 30 years have completely changed geologists' understanding of mountains. Rather than existing as permanent and fixed structures, mountains are young and active features of the Earth; in geological terms, they form quickly and collapse just as rapidly.