THE GREAT FLOODS - Cataclysms of the Ice Age

Name______________________________________________PER.________ Date ______________

1. Who was the man who first had the theory about the great floods?

J. Harlan Bretz

2. What was the first type of flood that hit Washington?

A flood of lava (Columbia River Flood Basalts)

3. What caused Lake Missoula?

An ice dam during the last ice age blocked the Clark Fork River in northern Idaho.

4. How deep was this ancient lake?

2,000 feet deep, deeper than any lake in North America today.

5. How was all of this water released from the lake?

The ice dam broke releasing 500 cubic miles of water, bigger that Lake Erie today.

6. How fast did the flood move through Washington?

A wall of water 800 feet high moved across Eastern Washington at 65 mph.

7. How was the Grand Coulee formed?

The ice sheet blocked the Columbia where Grand Coulee Dam is today. The ice dam diverted the Missoula Floods over land through the Grand Coulee.

8. How wide and tall was Dry Falls?

It is three and a half miles wide and 400 feet high.

9. How did a lot of the huge boulders travel so far?

They floated in icebergs.

10. What happened to the flood water at Wallula Gap?

The Wallula Gap caused the flood waters to back up and pool, creating an enormous temporary lake. Much of the flood setiment settled to the bottom.

11. How many times was Washington hit by these floods?

The ice dam on the Clark Fork broke and rebuilt itself at least 100 times over a 2,000 year period.

12. a. List the hard evidence that there was indeed a great flood.

Canyons and coulees of Eastern Washington, giant rocks, layers of flood setiment, giant ripple marks in Montana, dry falls.

b. What is the key piece of evidence that convinced other scientists?

The giant ripple marks found in Camus Prairie, Montana prove that there was an enormous ancient lake there.