When did the Ice Age Floods affect the Columbia River Gorge?

Asked By: Benedito Mieles | Last Updated: 9th May, 2020
Category: science geology
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Missoula floods
Glacial Lake Columbia (west) and Glacial Lake Missoula (east) are shown south of Cordilleran ice sheet. The areas inundated in the Columbia and Missoula floods are shown in red.
Date Between 15,000 and 13,000 years ago
Location The current states of: Idaho, Washington, and Oregon
Cause Ice dam ruptures

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Subsequently, one may also ask, was there a flood after the ice age?

The Missoula floods (also known as the Spokane floods or the Bretz floods or Bretz's floods) refer to the cataclysmic floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. The glacial flood events have been researched since the 1920s.

Secondly, what landscape did the Missoula Floods form? The flood waters of Lake Missoula also created giant gravel ripple-marks on the Camas Prairie in northwestern Montana. These ripple marks are found on the bottom of what was once Glacial Lake Missoula. These ripple marks are almost 50 feet high and have a wavelength of almost 500 feet.

Regarding this, how many times has Lake Missoula flooded down the Columbia River?

It was the largest ice-dammed lake known to have occurred. The periodic rupturing of the ice dam resulted in the Missoula Floods – cataclysmic floods that swept across eastern Washington and down the Columbia River Gorge approximately 40 times during a 2,000 year period.

How did the Bretz floods change the Columbia Plateau?

The key to the rapid erosion, Bretz said, was the volcanic basalt that forms the bedrock of the Columbia Plateau. So a massive, high-energy flood could pluck apart the bedrock so quickly that a canyon like the Grand Coulee might be formed virtually overnight.

15 Related Question Answers Found

Where did the flood waters go?

The country is semi-arid, meaning that much water disappears through evaporation and absorption. As the floodwaters moved downstream, they spread out onto the floodplains, filling local lakes and wetlands via a complex network of anabranches, creeks and billabongs.

How did the flood that formed the Scablands happen?

Large potholes were formed by swirling vortexes of water called kolks scouring and plucking out the bedrock. The Scablands are littered with large boulders called glacial erratics that rafted on glaciers and were deposited by the glacial outburst flooding.

When did Missoula Flood?

Missoula floods
Glacial Lake Columbia (west) and Glacial Lake Missoula (east) are shown south of Cordilleran ice sheet. The areas inundated in the Columbia and Missoula floods are shown in red.
Date Between 15,000 and 13,000 years ago
Location The current states of: Idaho, Washington, and Oregon
Cause Ice dam ruptures

What caused the ice age?

An ice age is triggered when summer temperatures in the northern hemisphere fail to rise above freezing for years. The onset of an ice age is related to the Milankovitch cycles - where regular changes in the Earth's tilt and orbit combine to affect which areas on Earth get more or less solar radiation.

Was there an ice age?


The Pleistocene Epoch is typically defined as the time period that began about 2.6 million years ago and lasted until about 11,700 years ago. The most recent Ice Age occurred then, as glaciers covered huge parts of the planet Earth.

What was the largest flood in history?

Great Flood of 1844. The Great Flood of 1844 is the biggest flood ever recorded on the Missouri River and Upper Mississippi River, in North America, in terms of discharge. The adjusted economic impact was not as great as subsequent floods because of the small population in the region at the time.

How was the Grand Coulee formed?

Geological history. The Grand Coulee is part of the Columbia River Plateau. This area has underlying granite bedrock, formed deep in the Earth's crust 40 to 60 million years ago. The land periodically uplifted and subsided over millions of years giving rise to some small mountains and, eventually, an inland sea.

What is the origin of the Columbia River?

Columbia Lake

What happens if Grand Coulee Dam Breaks?

If the dam could not hold back an excessive amount of water, the water would come over the top of the dam and potentially flood areas downstream, including cities.

When did Harlen Bretz propose the Channeled Scablands Megaflood story?


Bretz coined the term Channeled Scablands in 1923 to describe the area near the Grand Coulee, where massive erosion had cut through basalt deposits. The area was a desert, but Bretz's theories required cataclysmic water flows to form the landscape, for which Bretz coined the term Spokane Floods in a 1925 publication.

Are there deserts in Washington state?

Eastern Washington is the portion of the US state of Washington east of the Cascade Range. Unlike in Western Washington, the climate is dry, including some desert environments.