Diatomite from Quincy, WA.
While driving along Interstate 90 in Eastern Washington, heading towards George, Washington, you will see large white deposits sandwiched between basalt layers. These white deposits are the Quincy Diatomite. Located not too far from George, is the small town of Quincy that mines the diatomite. Washington is among the top four states that produce diatomaceous earth for commercial use.
Early in the Miocene a hotspot in the earth’s mantle formed under the area where Idaho, Oregon and Washington meet. The volcanic vents opened up and liquid lava poured out across the area. In this area of Washington, it is believed that a large lake existed where the ancestral Columbia River was blocked by previous lava flows. These volcanic events not only produced the lava that damned the rivers making lakes, it also supplied a large amount of ash rich in silica that fell in to water sources that drained into the lake.
Although most sources of silica do not dissolve easily in water, the silica in volcanic ash does. The abundance of silica in the lake waters provided an excellent source for the rapid growth of the diatom population. Diatoms extract the silica from the water to produce their shells or frustules. When diatoms die their shells will fall and accumulate on the floor of the lake. Because of the abundant supply of silica there was a rapid rate of accumulation.
During the Miocene the volcanic activity was high and produced a number of lava flows. The Columbia River Basalt flows of the Rosa member flowed over the diatom deposits sandwiching it between two lava flows. During the Ice Age floods, the floods scoured the basalt and much of the diatomite, sending the sediments down through the Columbia River and out to the Pacific Ocean. There are erosional remnants of the diatomite left along the margins of the Frenchman Coulee and the Echo Basin.
Diatoms are single cell organisms are phytoplankton that can live as individuals or live in colonies. They can be found in all waters whether marine or lacustrine, from the tropic to the Polar Regions. The tropical area produces more species but the cooler polar waters have larger populations. They live at or near the surface in an open water column. Most diatoms need sunlight because they get their energy through photosynthesis. They are very abundant and are the producers within the food chain contributing up to 45% of the oceans food source.
Diatomite is a white, soft, fine-grained sedimentary rock that has a chalk-like texture. It can float on water, because it is very porous and low in density, until it becomes saturated. Because of its porosity it is desired commercially as a filtering substance. It’s extensively used as a filter in the making of beer, wine, oil and greases. It is also used to filter water removing bacteria and protozoa.
The diatomite in the picture to the right is on private land with No Trespassing signs.
Below is a sample of Diatomite from Washington that was included in a fossil specimen kit.
Bruce Bjornstad 2006
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Bjornstad, Bruce, 2006. Ice-Age Floods through the Western Channeled Scabland: Some Highlights of the Upcoming Field Trip. The Pleistocene Post: Quarterly Newsletter of the Ice Age Floods Institute, vol.3, issue 1, March 2006. February 20, 2010.
Mineral Information Institute (Content Partner); Sidney Draggan (Topic Editor). 2008. “Diatomite.” In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth January 21, 2008; Last revised January 22, 2008; Retrieved February 18, 2010]. http://www.eoearth.org/article/Diatomite
Werner, D. ed., 1977, The Biology of Diatoms, Botanical Monographs, University of California Press, v. 13, 498 pp.