Columnar Basalt: Nature’s Art

These tall pillars look like an artist carved them out of stone for the purpose of ornamentation, but they are actually a beautiful record of how chemistry and geology play an interconnected role in nature. A remarkable visual remnant of the ancient lava flows of the Pacific Northwest

From as much as 17 million years ago, the entire Columbia Basin region has undergone many outbreaks of lava flows, each of which separated by thousands of years, and cover as much as 81,000 square miles and up to 3 miles deep in some areas (Reidel, 2015). These massive flows of lava cooled at different rates, the top and the bottoms first, which are called entablature. Entablature is a haphazard, broken-up looking formation of the top and bottom of a lava flow, and they look like this because the exterior of the lava flows cooled faster, and therefore did not have the time to cool in the same way as the interior columns. As the lava cooled inside the flows, each column pulled inward toward a central point, creating the gaps, or fractures, called columnar jointing (Conrad, 1938). These gaps made them much easier to get pulled apart during the big floods.

Around 16,000 years ago, when the Missoula Floods came ripping through this area, much of the top layer of sediments and other rocks were washed away, exposing the layer of basaltic pillars to the flood water. Some of these individual pillars were then “plucked” out very easily by large kolks (underwater vortex created by fast moving water moving across objects), and washed away to be dropped somewhere else down the line (Baker, 2009). These picked apart basalt column formations are what we see all over the Columbia Basin region and in parts of Idaho and Oregon today.

Images

Beautiful Basalt....columns

Beautiful Basalt....columns

Creator: Karissa Linn View File Details Page

Photo of columnar basalt in the Priest Rapids Member of the Wanapum Basalt

Photo of columnar basalt in the Priest Rapids Member of the Wanapum Basalt

Creator: Karissa Linn View File Details Page

Columnar Joint Formation

Columnar Joint Formation

Source: Washington Dept. of Natural Resources View File Details Page

General Basalt Structures

General Basalt Structures

Source: Reidel, S. P., 2015, The Columbia River Basalt Group: A Flood Basalt Province in the Pacific Northwest, USA, in Kerr, Andrew, ed., Geoscience Canada, Volume 42: Canada, Geological Association of Canada, p. 151-168, doi: http://dx.doi.org/10.12789/geocanj.2014.41.061 View File Details Page

Cite this Page:

Karissa Linn, “Columnar Basalt: Nature’s Art,” Ice Age Floods Explorer, accessed October 22, 2017, http://floodexplorer.org/items/show/52.

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