Ice Age Floods, Lake Missoula, Bonneville Flood and the Columbia River Basalts

the Pacific Northwest is famous for many things including huge floods floods of lava that buried almost 40% of Washington and floods of Ice Age water that created more than 2,000 square miles of scablands what are the odds that such rare events both happened here in this corner of North America we're just south of Lewiston Idaho at the mouth of Hell's Canyon the lowest point in the state the basalt bedrock here the floods of lava came out of deep cracks that formed in response to a heat source that's now in the state of Wyoming a flood of water from a giant lake in Utah came all the way through southern Idaho through Hell's Canyon dropped rocks here and the water made it to the Pacific Ocean a giant lake in Montana flowed to the Cascades got backed up to here each of these layers representing a separate flood the Columbia River basalts the bottle he'll flood and the Missoula floods let's dig in together and learn about huge floods in the Pacific Northwest the ice age floods have helped expose an incredible pile of lavas from erupting volcanoes that are not related to our famous cascade volcanoes the Columbia River basalt a pile of lava rock more than 2 miles thick is an exception to the global rule basalt lavas usually erupt in ocean basins but these low silica lavas flooded North America from below much like a boat with a leak there are similar flood lavas in central India southern Brazil southern Africa and Central Siberia in each case very large volumes of fluid basaltic magma erupted rapidly from cracks and continents to form sheets of lava rock covering tens of thousands of square miles the deep cracks called fissures cracked the North American crust in southeastern Washington and eastern oregon starting 17.5 million years ago today many geologists agree that the fissures are directly related to the birth of a tectonic hot spot beneath out south eastern oregon 17 and a half million years ago and now located underneath Yellowstone National Park in Wyoming due to the North American plate slowly moving over the stationary hotspot these spectacular basalt lava eruptions more than three hundred distinct events punctuated by thousands of years of quiet between each lava flood flooded and buried the rugged inland landscape of the Pacific Northwest many of the biggest lava flows made it from their fissures near Idaho all the way to the towering cliffs of the Oregon coast at Pasco Washington the stack of Columbia for basalt lava flows is 16,000 feet thick more than three miles of lava sitting on top of a 17 million year old landscape there isn't one Vista to see all the lava flow years how could you to truly grasp the scale of the lava stack one has to visit scattered canyons that expose a dozen flows at a time like in the Yakima River Canyon in the Columbia River Gorge or in the Grand Coulee which was carved just thousands of years ago not millions by the Ice Age floods during the Ice Age a thick ice sheet covered much of North America advancing and retreating in response to changing global climate in Washington Canadian ice crossed the border in different places west of the Cascade Range the Puget lobe filled the Puget lowland with 3,000 feet of ice above present-day Seattle with the enormous erratic left behind after the ice melted back most Puget Sound residents live on complicated sets of Ice Age deposits glacial till glacial outwash that reveal ice on the move advancing and retreating with glacial lakes riding the front of an active ice margin east of the Cascades the Okanagan lobe crept into North Central Washington gorgeous glacial moraines and impressive glacial erratics have been sitting on the Waterville plateau for at least 12,000 years during some of the Okanagan ice advances the mighty Columbia River was diverted and sent due south through the Grand Coulee and overdry Falls in northern Idaho the Purcell lobe combined with the rugged topography of the Bitterroot Mountains and blocked Montana's Clark Fork River near present-day Sandpoint Idaho glacial lake Missoula formed as glacial meltwater backed up behind the ice dam forming a huge lake more than three thousand square miles of western Montana old shorelines of the lake are visible above the University of Montana faint water marks first noted in 1886 by tea see Chamberlain the lake was 950 feet deep at Missoula and up to twice that depth in neighboring valleys and then it happened glacial lake Missoula breached the ice dam and raged across Eastern Washington through the Cascade Range and reached the mighty Pacific Ocean up to ten cubic miles per hour a rate 10 times the combined flows of all the rivers on planet earth surged through Eddy Narrows and other narrow valleys in western Montana when the huge lakes suddenly drained giant current ripples were created on the lakes floor and the failed ice dam was replaced by a new one and another glacial Lake Missoula formed which led to the next Missoula flood drama repeated many times banded deposits at the bottom of glacial lake Missoula show the lake formed dozens of times and released quickly over Washington each time rinse and repeat up to 100 times these are slack water sediments from the Missoula floods we're in Tammany barges south of Lewiston Idaho each of these is a separate Missoula flood for 150 miles upstream from lilulu gap that means water from Montana made it to WA Lula Gap and had to back up this far up the Snake River drainage this is one event silt falling from the bottom of Lake Lewis and another flood and another flood now that's amazing meanwhile another Ice Age flood the Bonneville flood happened around the time of Missoula flooding Lake Bonneville an Ice Age predecessor to the Great Salt Lake filled and spilled out of Utah and into southern Idaho the old shorelines of Lake Bonneville ancient bathtub rings above Salt Lake City were first described by GK Gilbert in 1890 a desert under water once the Bonneville Basin was filled to capacity seventeen thousand four hundred years ago erosion of loose rocky material at Red Rock pass led to the rapid lowering of Lake Bonneville and the Bonneville flood surged north into Idaho Snake River plain unlike the Missoula floods and it's ice dam the Bonneville flood involved a lot more water than the biggest Missoula flood probably about twice as much water but the constriction at Red Rock past that it spilled out through was much smaller than where the ice dam was breached in northern Idaho the Bonneville water came out slower so while the volume of Bonneville water was twice as large as the largest Missoula flood the peak discharge was only about one tenth of the largest Missoula flood each Missoula flood lasted four days the Bonneville flood lasted four weeks gorgeous deposit all these rocks were deposited by the Bonneville flood just one flood right just a few weeks all these rocks were dropped seventeen thousand four hundred years ago sitting on top our Missoula flood sediments there are 20 different Missoula flood layers here so at this spot we had 20 Missoula floods after the Bonneville flood so how do we know this stuff carefully crafted geologic maps made in the field by generations of geologists have measured both the erosional chasms cut by the floods and have catalogued piles of rocks and layers of sediment that the floods have left behind water scarce here in Eastern Washington today it's a desert but the landscape has a strong stamp of water and lots of it the Ice Age floods tore up the crust revealing the Columbia River salt low VA's that flowed millions of years earlier cleaving dramatic landmarks like the Grand Coulee dry follows the criss-crossing flood paths of Drumheller channels and Palouse Falls tons of bedrock were hauled away by the floods as the water exploited deep cracks in the bedrock box-shaped valleys called coolies formed where the most aggressive water did the most digging rock pre-cut and hauled off by the floodwater cruising at more than 60 miles per hour in places and there are amazing potholes drilled by the swirling dynamics in the floodwater often revealed in the vertical Coulee walls cut by the erosive Ice Age floods lost worlds hidden in basalt bedrock at the bottom of key lava flows pillow structures were lava battled Lake water and petrified logs provide detailed clues to the ancient forests and lakes that thrived in eastern Washington during the thousands of years between devastating lava floods that repeatedly buried a vibrant thriving ecosystem in thick lava a landscape full of life with each lava burial creating a lifeless featureless moon scape millions of years later each of the 100 floods made it to the Pacific Ocean but does that mean that each flood maintained a high speed from Montana to the coast no like today there are many obstacles to negotiate on a journey from the Rockies to the Pacific Ocean the Ice Age floods had the same roadblocks will Lulla gap the Eastern Gateway to the Columbia River Gorge was a bottleneck for the floods every drop of Ice Age floodwater needed to squeeze through the gap which was the secret passage through the Cascades and on to the Pacific at will Oologah floodwater waiting to enter became Lake Luis the bigger the flood the larger the lake Luis calm and dirty brown with suspended loose which crept up neighboring river valleys the Yakima River the Walla Walla River and the Snake River the water of Lake Lewis must have gotten clearer with each passing day the fine grain material falling out of the lake and onto the lake bottom the result impressive layers of slack water sediment each layer from each Lake Luis and the surface of Lake Luis was full of icebergs how do we know that there are large erratic s' all across Central Washington that marks spots where the icebergs drifted to the edge of the lake upstream some of the largest Missoula floods came down the Columbia River over Wenatchee and downstream from Wenatchee West bar is a classic location to ponder the speed and depth of the floods you old enough to remember the media frenzy over Evel Knievel's daredevil jump over the Snake River Canyon that's the canyon that the Bonneville flood the one from Utah flowed through remember Lake Bonneville spilling over Red Rock pass and into the Snake River drainage of southern Idaho the flood scoured canyon walls and gouged holes in the canyon floor creating shoshone Falls and twin falls the water ripped through the narrow reaches of the canyon dislodging basalt boulders and tumbling them downstream where the flood channel widened the boulders were heaped into impressive piles the Bonneville flood then entered Hells Canyon the deepest Canyon in North America before joining the channeled scablands of Eastern Washington the deposits left by the flood give us rich detail giant flood bars more than 100 feet above today's Snake River sit in narrow stretches of Hells Canyon showing us where the flood got choked up creating flood stages hundreds of feet high behind it and slack water sediments are found all through the Bonneville flood route but not the repetitive slack water sediments like the Missoula floods remember there was just one Bonneville flood all told 100 different layers of slack water sediment have been documented in eastern Washington 100 Missoula floods but there is work yet to be done what's the age of each flood is a more complete record of the Ice Age floods sitting in the Pacific Ocean at the mouth of the Columbia River and with the floods of lava why did such pure oceanic lava flood a continental scene and how did the lava stay molten for 300 miles much yet to be determined with our huge floods in the Pacific Northwest

Channel: hugefloods

Views: 171,982

Rating: 4.9204059 out of 5

Keywords: Ice Age Floods, Lake Missoula, Missoula Floods, Lake Bonneville, Bonneville Flood, Columbia River Basalt, Basalt, Columnar Basalt, Scabland, Seattle geology, Pacific Northwest, Nick Zentner, Channeled Scabland, Hells Canyon, Tammany Bar, Lewiston, Idaho, Yellowstone Hotspot, Snake River, Wallula Gap, Grand Coulee, Salt Lake, Palouse Falls, Dry Falls, Drumheller Channels, ice age, pleistocene

Id: i1BFb_uYlFQ

Length: 16min 17sec (977 seconds)

Published: Mon Dec 08 2014

Reddit Comments

[u/challam]

Thanks! Your videos are always a huge treat.

[u/PotentialApathy]

Great video. Do you have any suggestions for a self-guided tour of the major flood landmarks? I live in Vancouver and have been meaning to do this for some time.

[u/Enneirda1]

These videos make PNW geology so accessible, thanks for sharing!

[u/TroubleYouForTheSalt]

Really glad you're still making videos! Well made as always!

[u/Taint_Guche_Grundle]

I need to check some of this area out. I'm from the southwest but I have family in south west Oregon and south central Washington. I'd really like to see some columnar basalt and the ripples left by the giant floods. Thanks for the video.