A Bridge Into Prehistory

Benson Bridge at Multnomah Falls, Oregon, is a gorgeous overlook at one of many spectacular falls in the Columbia River Gorge. It is also a glimpse into the ancient world. In geologic terms, the glimpse is fairly recent, mammals were the dominant vertebrates when the Earth laid the groundwork for the tourist attraction. However, it is amazing to be reminded that the world was still a frightening display fire and ice even when mammals dominated the Earth.

Multnomah Falls has carved the rock around it into a curved amphitheater-like structure, displaying the relentless power of water over millions of years. The lichen and moss-covered rock—all 662 feet—is basalt, an igneous rock formed as lava cools. Basalt is more commonly found in ocean basins when lava mingled with the deep ocean waters along the ocean floor.  Island chains, like Hawai’i, are also formed from volcanic basalt. So, what is a basalt canyon doing in Oregon?

The basalt that Multnomah Falls cascades down is part of the Columbia Plateau. This rock formation was formed between 10 to 15 million years ago. Lava poured out across present day Washington, Oregon, and Idaho through cracks in the Earth’s crust. Over millions of years uplift in the region rose the basalt flats, and the Columbia River cut through the area creating the Columbian River Gorge. More recently in geologic history were the Ice Ages. The freeze and thaw cycles during the Ice Age supplied the water that would erode through the basalt to create the spectacular Multnomah Falls. Melting snow and a natural spring, still feed the falls to this day.

This is what you are truly looking when looking at these looking at these pictures. This one post was 15 million years in the making. This is the slow, but relentless, dance of our Earth.

In 2014, a year after I took these pictures, a large piece of rock broke free from the falls and damaged the railing and bridge walkway. It was repaired, but it is a reminder that these processes will continue and everything will be unrecognizable in another 15 million years.



Benson Bridge just above the base of the Falls.


Looking over Benson Bridge to the Falls below


Looking out at the main Falls and the basalt canyon behind it

© 2016 C.J. Staryk. All Rights Reserved.



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1 Response to A Bridge Into Prehistory

  1. Thee benson bridge and falls looks quite spectacular!


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