Greetings fellow humans!
I am Ruby T. Gray, Neil, or Neilly; just don’t call me late for dinner. Welcome to Cooperative Culture Learning! This is my first video on topics that I find interesting and just wanted to share. My hopes are that my friends, and other parents who are homeschooling, can use this video and future ones for educational purposes. Otherwise, I’m just talking about things I find neat!
Please note that I cite my sources in all show notes. I will do my best to paraphrase all research I find to give the most genuine experience.
Our first video from “Cooperative Culture Learning” is going to be about the Missoula Ice Floods that occurred during the last Ice Age. This series mega-flood is what shaped the landscapes of Western Montana, Northern Idaho, Eastern Washington, the Columbia River Canyon, and the Willamette Valley in Oregon. Let’s begin our journey.
“Picture it, Western Montana, during the last Ice Age, that ended approximately 10,000 years ago.”
The Pleistocene and late Pliocene Epochs brought on a progression of interglacial periods; followed by periods of advancement. Approximately 2.5 million years ago and ending approximately 10,000 years ago (or YBP - Years Before Present). “As much as a third of Earth's land surface was periodically covered in ice during this time” (Ray, 1993).
The Cordilleran Ice Sheet covered Washington, Idaho, and Montana; containing three main lobes. The Puget Lobe, The Okanogan Lobe, and The Purcell Trench Lobe. The Puget Lobe created the Puget Sound in Western Washington. The Okanogan Lobe created Glacial Lake Columbia, believed to be at the present location of the Grand Coulee Dam. The Purcell Trench Lobe dammed the Clark Fork River; this formed Glacial Lake Missoula.
It is believed that the formation of Glacial Lake Missoula began 80,000 YBP and ended around 10,000 YBP.
Once the glacier efficiently dammed the Clark Fork River. Glacial Lake Missoula began to form, with water building up and forming eastward; approximately 200 miles into Eastern Montana. The result created the Flathead River Valley. At its fullest, Glacial Lake Missoula had a depth of 2000 ft (at the dam), and it held 500 cubic miles of water. This is greater than Lake Erie and Lake Ontario combined!
Once the water in Glacial Lake Missoula reached its maximum height of 4,200 ft, there was a pressure being placed upon the glacier. This led to the creation of subglacial tunnels. These tunnels would ultimately be the cause of the dam’s collapse.
The waters of Lake Missoula burst through the ice dam at speeds (estimated to be) up to 65 MPH. Taking a few days to a week to fully drain.
From the dam at the Clark Fork River, the waters of Glacial Lake Missoula embarked on a 430-mile journey to the Pacific Ocean.
As the massive floodwaters moved West (Northern Idaho, Eastern & Central Washington) ice and glacial debris chiseled, chipped, and sculpted the land beneath it. This deepened and widened the Columbia River Gorge, the deepening the river channel that was suppressed by a narrow gap near Vancouver, WA.
The narrow gap caused the floodwaters to spillover into Oregon’s Williamette Valley. This created a lake that stretched as far south as Eugene, Oregon. By the time all floodwaters had emptied into the Pacific Ocean, they had 430 miles of land behind them.
This was not a single occurring event, but a “collective sequence” as the dam formed and collapsed as the Cordilleran Ice Sheet advanced and recited over at estimated 2,500 years. This caused multiple floods over Northern Idaho, Eastern & Central Washington and the Columbia River Channel. These are known as “Ice Age Floods”.
The everlasting effects of the Ice Age Floods on the landscape of the PNW.
The floodwaters left the landscape of the PNW scarred, rippled, and watermarked. Leaving the trail in erosional and depositional clues that modern geologists can follow to this day.
As Glacial Lake Missoula filled, the waters left shoreline “clues” that were visible in the hillsides outside of Missoula, Montana; these are known as “paleo-shorelines”. These paleo-shorelines reached heights of 4,200 ft elevation, the maximum height believed to be reached by the waters of Glacial Lake Missoula.
The floodwaters created these giant ripple marks in the Camas Prairie of Western Montana. Giant ripple marks like these are typically found on the bottom of glacial lakes, like Lake Missoula. Measuring from 35 to 50 feet in height, and wavelengths several hundred feet. Ripple marks of these magnitudes are only made with astonishing currents of enormous power over the ancient lakebeds. These ripples are the most convincing evidence that these Ice Age Floods occurred.
As we travel through the Columbia Plateau and River Valley (heading East to West); we can see evidence of these catastrophic floods and the result of their unique ways of shaping the landscape.
As water flowed through Eastern & Central Washington, topsoil and bedrock were stripped away; carving the Scablands into the Earth.
The Scablands in Eastern Washington is composed of an intertwined network of Loess Islands, flood channels, cataracts, coulees, and plunge pools.
Side notes and FYIs - Loess Islands are an ecoregion that consists of loess deposits, that are surrounded by the Channeled Scablands that are sprinkled in Eastern Washington. Loess is “a loosely compacted yellowish-gray deposit of windblown sediment of which extensive deposits occur” (from Dictionary dot com.). Loess is generally created by wind, but can also be formed by glaciers. “When glaciers grind rocks to a fine powder, loess can form. Streams carry the powder to the end of the glacier. This sediment becomes loess.” (source #5)
As water rushed over the land, it left giant waterfalls. Three of these are still visible, standing, and some still active. These three are Grand Coulee, Dry Falls, and Palouse Falls are to name a few.
Dry Falls absolutely lives up to its name in modern days. However, Dry Falls was once considered to be the largest waterfall in North America. Today, it is a state park and recreation lake. At its peak, Dry Falls was estimated to be 3 times as wide and 2 ½ times as tall as Niagara Falls.
Palouse River Canyon was formed from the debris and water currents of the Ancient Ice Floods. Today, Palouse Canyon is known to be a modest creek, in the center of Washington State’s “Grand Canyon”. Palouse Falls is one of the very few active waterfalls left behind by the Ancient Ice Floods.
Grand Coulee is what remains of ancient river beds. The Grand Coulee spans 60 miles southwest of the Grand Coulee Dam to Soap Lake. Dry Falls separates the Upper and Lower Grand Coulee.
The largest of the floodwaters engulfed The Saddle Mountains. The Saddle Mountains reach 2,664 ft, in Grant County, Washington.
As the water traveled through the Columbia River Gorge, widening and deepening as it rushed over the land, basins, and river beds. Down the Columbia River, several gaps narrow to give the bottleneck effect. One of these being the Rowena Gap (or the Rowena Gap/Ortley Gap). The waters reaching heights up to 1,000 ft and the ancient shorelines can be seen today in the towns along the Columbia River.
Scattered throughout the Columbia River Gorge (as you drive down I-84 and Wa Hwy 14), you will notice some of the almost vertical that walls the gorge. The floodwaters enhanced the cliffs by causing soft materials to erode away. Multnomah Falls is the second-highest year-round waterfall in the U.S.
This entire time these waters are rushing and shaping the lands, there are ice chunks, debris, trees, rocks, boulders, and more racing with the floodwaters. This all jammed up the water and caused it to overflow south towards Eugene. As the waters emptied into the Pacific Ocean, they left the land with the topsoil from the Scablands. Creating the ideal fertile land for farming in modern-day Oregon.
The waters also left behind “glacial erratics”, or rocks from somewhere else. It is thought that icebergs (from the ice sheet) carried massive boulders to their current place throughout the Willamette Valley. These icebergs stayed as the waters receded; once the ice had melted, the bulders remained. These boulders can be traced back to British Columbia and Montana.
Now, believe it or not, this was not always the widely accepted theory as it is today. Geology is still evolving, especially as technology increases. The geological “standard” has changed over the last 100 years or so and will continue to evolve. Science is ever-changing, as humans should be as well.
In 1910, the theory that glaciers dammed the Clark Fork River and causing the massive lake existed. However, it was never discussed what had happened to the waters. This led to a paper being published by the USGS (United States Geological Survey).
In 1923, J. Harlen Bretz spent the majority of his career and life studying the unique landscapes of Eastern Washington. He coined the phrase “Channeled Scablands”. Bretz was the first to publish a paper on the hypothesis that massive amounts of water formed the Scablands and other features.
Unfortunately, this theory was not widely accepted within the geological and scientific communities. The community was running on the accepted “Principles of Uniformitarianism ”; this is the idea that evidence of major geological events can be created by explainable, visible forces. Since floods of those proportions have never been seen, the idea was immediately dismissed.
Until 1942, Joseph T. Pardee published a paper with evidence of the mega-ripple marks. Due to the size of the ripple marks that were left behind, Pardee stated that these ripple marks were formed by swift and deep flowing currents; to be caused the collapse of the ice dam that was clogging the Clark Fork River. This provided Bretz with the evidence he needed.
It wouldn’t be until the 1970s when satellite imagery was able to give a bigger picture of the landscape that was scarred and formed by the massive waters of Glacial Lake Missoula and the Missoula Floods.
Today, the scientific community is at a debate on the numbers of floods, frequency, and sources. With some theories discussing the idea of the other glacial lobes having the same effect as Glacial Lake Missoula.
What we can say “for sure” is that the Earth is a giant puzzle of mystery to us Humans, and we have only begun to tap into its secrets. We use tools, such as Geology, to help us tell the stories and understand our world a bit better. Though when it comes to ancient floods, we are using our best guessing techniques or hypothesis.
Wrap up: Sources, next episode, and spanks for coming!
The sources I used for this compellation are the following:
https://www.pbs.org/wgbh/nova/megaflood/scab-nf.html - Nova has some amazing interactive features on this topic and is where I got a lot of my facts from. I highly recommend Nova & PBS.
http://geology.isu.edu/Digital_Geology_Idaho/Module13/mod13.htm
http://columbiariverimages.com/Regions/Places/missoula_floods.html#rowena_gap
https://en.wikipedia.org/wiki/J_Harlen_Bretz#The_Spokane_floods:_an_outrageous_hypothesis
For my next episode, I’ll be bringing more PNW geology your way and I plan on launching a “bonus” episode of something LESS technical. My goal is to work on two topics; one heavy science and the others will be “oopsie” sciences. Such as, mistakes that made it to consumerism.
If there is anything you’d like for me to cover, I am constantly adding to my list of topics! I’m open to constructive criticism, but please be kind (nervously laugh & shifty eyes) as I am fresh to the world of making videos and sharing them. My knowledge is of Instagram stories and Tik Tok.
Thank you for coming! If you enjoyed this, please “like, comment & share”. Also, please subscribe. You can follow me on all the social media platforms.
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Thank you for taking the time to watch my video! I hope you gained some knowledge and can pass it along to others. Until next time, babes!
Sources:
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