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How the Columbia River Gorge Was Formed
How the Columbia River Gorge Was Formated
by Toni W. of GorgeConnection.com
The Columbia River Gorge formation started approximately 40-60 million years ago. The granite from within the earth was lifted up from the pressure of molten lava from inside the earth which caused the outline of the Columbia Basin.
The granite lifting was only the beginning though. Approx. 10-15 million years ago, the formation continued as the area was flooded with lava flows due to volcanic eruptions in Western Idaho, Eastern Washington and Eastern Oregon which flowed as far as the Pacific Ocean. This lava consisted of ash, lava and mud.
The cracks that released the molten lava were as many as 270 across the region. Approximately 21 of those poured lava into the Gorge. It is believed that many layers of lava contributed to the 2,000 to 5,000 feet of thickness and smooth surface of the Columbia Plateau. The amount of lava from these flows is estimated to be 41,000 cubic miles.
During the cooling process, it cooled slower at the base than the top, causing six sided columns and walls to form, less uniformly at the top. This shows in the basalt walls and pillars of the Gorge. Some of these "volcanoes" are still visible, although listed as dormant. They can be seen on a clear day from Hood River, Mt. Hood and Mt. Adams.
Approximately 2 million years ago, there was an ice age. During this period, glaciers pushed down helping form the Cascade Mountain Range. The mountains were unable to block the flow, cutting the deep Columbia Gorge.
At the end of the ice age, the Cascade Volcanoes rose, 100's of them forming the Cascade Range. Some of the mountains were sculpted by glaciers, others remained as they were.
Following the ice age, the Columbia River returned to her former channel. Large pillars and walls were left above the flow of the river. Some of these measure 500 to 1600 feet above the river floor.
About 1800 years ago, the Columbia Basin became flooded when an ice dam broke at Lake MIssoula in Western Montana. This lake help approximately 600 cubic miles of water. Boulders were tossed around the outlet of the break. Others were carried in icebergs as far as Western Oregon towards the Pacific Ocean. The water flowed at appoximately 60mph. It is believed that it took 2-3 days for this water to drain.
During a period of 2500 years, there were believed to be as many as 100 floods that scoured the Gorge area. These were some of the largest documented floods occuring on the planet and in geological history.
The geological history of this area is unique and quite unusual. There are parts along the Gorge that if being searched out and observed, leaves and pieces of trees in the rocks can be found. This was due to their presence prior to the lava being completely cooled. To this day, a good eye can still spot this cool happening in the Eagle Creek area of the Gorge.
The Eagle creek area is the only passage through the cascade range that is near sea-level. The area provides us some of the most amazing geological findings and history in the world.
Check it out and be sure to email us any cool photos that you find! They may just get posted here on this page!
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