Destructive Forces

DVD + 3-Year Streaming
3-Year Streaming
Destructive Forces (52:00)
Item# 40735

Why do mountains tend to have a triangular shape? How much rain must fall to start a river? How do single grains of sand accumulate into a dune? This episode from the Amazing Planet series answers those and other geologic questions by capturing the beauty born of eons of unceasing environmental violence as water, wind, and ice erode the surface of the Earth into an ever-changing sculpture of planetary proportion. A National Geographic Production.(50 minutes)

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Segments in this Video - (13)

1. Nature's Elements (03:20)
 Available for Free Preview

The warring elements of air, water, fire, and rock never call a truce in the history of the world. The cycle of rebirth and destruction begins at the Earth's core where magma is spewed to the surface.

2. History of the Grand Canyon (04:19)

Six million years ago, the spectacle of Grand Canyon did not exist.To understand how the Grand Canyon was formed, film viewers will go back 500 millions years ago in Earth's history and work their way up to today.

3. Natural, Sculptural Displays (02:28)

In the Southwest is much evidence of the power of erosion such in Canyons National Park and Monument Valley.

4. Destruction and Regeneration (05:26)

Given enough time, rivers move mountains. Rivers scour the planet's surface. The Earth is engaged in a continual cycle of destruction and renewal. This is called the "rock cycle." Landslides come in many types and levels of danger.

5. Niagara Falls (05:17)

Waterfalls are Earth's roller coasters. Niagara Falls rises 200 feet in the air and has spawned a massive tourist trade. Glaciers set the stage for the Falls. Dolomite is the capstone of the Falls.

6. Waterfalls and Cataracts (04:56)

Some waterfalls are generated by rain, not glaciers. In other parts of the world, waterfalls are caused by the heaving and thrusting of the earth--plate tectonics. Waterfalls and cataracts featured include Angel Falls and Victoria Falls.

7. Caves: Water's Patient Power (03:55)

All seven continents have enormous caves caused by the patient action of water on limestone. A sinkhole is a cave whose roof has caved in. Photography reveals the stunning beauty of cave interiors.

8. Water: Frozen Brutality (04:54)

In the distant past, ice ruled the world. Water wears down mountains, creates caves, and makes the huge sheets of snow and ice called glaciers. They hold 3/4 of the earth's fresh water. They shape the earth's surface.

9. Glacial Catastrophes (01:39)

Ice sheets can unleash catastrophes such as the scab lands in the Pacific Northwest. Aerial photography shows the devastating damage to Earth's surface when a massive flood swept through Idaho, Oregon, and Washington 16,000 years ago.

10. End of the Age of Glaciers (02:33)

Evidence suggests that the earth is warming. The age of glaciers may be a thing of the past. Melt-water from the Greenland ice sheet could raise water levels by 20 feet.

11. Nature's Elements: Wind (02:52)

Black blizzards, red storms, and stinging and burning squalls are what happens when the wind turns the pulverized Earth against itself. The most forbidding domain of sand is the desert.

12. Global Shifting Sands (03:54)

The desert is an undulating sea of sand constantly shifted by the wind. Sands are blown all over the world, and with the sands come fungal spores that cause damage, but also brings nutrients to places like the Amazon Basin.

13. America's Dust Bowl (02:29)

In the 1930s, over-cultivation and drought led to black blizzards of soil and dust. In 1883, the volcanic eruption of Krakatoa sent a gigantic cloud of dust and ash into the atmosphere.

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