0:00:00.000,0:00:38.461 [Intro Music] 0:00:38.461,0:00:41.230 The Pacific Northwest is famous for many [br]things. 0:00:41.230,0:00:43.316 Including huge floods. 0:00:43.316,0:00:46.518 Floods of lava that buried almost 40%[br]of Washington, 0:00:46.518,0:00:51.655 and floods of Ice Age water that[br]created more than 2,000 square miles 0:00:51.655,0:00:54.725 of scab lands. 0:00:54.725,0:00:57.993 What are the odds that such rare events[br]both happened here in this corner of 0:00:57.993,0:01:00.413 North America? 0:01:00.413,0:01:04.250 We're just south of Lewiston Idaho at the[br]mouth of Hells Canyon, 0:01:04.250,0:01:07.335 the lowest point in the state. 0:01:07.335,0:01:09.220 The basalt bedrock here, 0:01:09.220,0:01:15.141 the floods of lava, came out of deep [br]cracks that formed in response to a heat 0:01:15.141,0:01:19.245 source that's now, in the state of[br]Wyoming. 0:01:19.245,0:01:22.981 A flood of water from a giant lake in Utah 0:01:22.981,0:01:27.153 came all the way through Southern Idaho,[br]through Hells Canyon, 0:01:27.153,0:01:31.847 dropped rocks here, and the water made it[br]to the Pacific Ocean. 0:01:31.847,0:01:34.056 A giant lake in Montana 0:01:34.056,0:01:37.750 flowed to the cascades, got backed up[br]to here. 0:01:37.750,0:01:41.738 Each of these layers representing a [br]separate flood. 0:01:41.738,0:01:44.178 The Columbia River basalts, 0:01:44.178,0:01:46.129 the Bonneville flood, 0:01:46.129,0:01:48.332 and the Missoula floods. 0:01:48.332,0:01:50.184 Let's dig into together and learn, 0:01:50.184,0:01:54.671 about huge floods in the Pacific [br]Northwest. 0:01:54.671,0:02:05.496 [ Music Plays ] 0:02:05.496,0:02:10.776 The Ice Age floods have helped expose[br]and incredible pile of lavas 0:02:10.776,0:02:16.679 from erupting volcanoes that are not[br]related to our famous cascade volcanoes. 0:02:16.679,0:02:19.550 The Columbia River basalt group, 0:02:19.550,0:02:22.868 a pile of lava rock more then 2 miles[br]thick, 0:02:22.868,0:02:25.972 is an exception to the global rule. 0:02:25.972,0:02:28.858 Basalt lavas usually erupt in ocean [br]basins, 0:02:28.858,0:02:33.360 but these low silica lavas flooded North[br]America from below. 0:02:33.360,0:02:36.330 Much like a boat with a leak. 0:02:36.330,0:02:42.173 They're similar flood in central India,[br]southern Brazil, southern Africa, 0:02:42.173,0:02:44.007 and central Siberia. 0:02:44.007,0:02:48.362 In each case, very large volumes of fluid[br]basaltic magma 0:02:48.362,0:02:53.431 erupted rapidly from cracks and continents[br]to form sheets of lava rock covering 0:02:53.431,0:02:55.934 tens of thousands of square miles. 0:02:55.934,0:03:02.607 The deep crack called fissures cracked[br]the North American crust in south eastern 0:03:02.607,0:03:08.691 Washington and eastern Oregon,[br]starting 17.5 million years ago. 0:03:08.691,0:03:12.994 Today many geologist agree that the [br]fissures are directly related to the birth 0:03:12.994,0:03:15.579 of a tectonic hot spot, 0:03:15.579,0:03:19.083 beneath the out south-eastern Oregon[br]17.5 million years ago, 0:03:19.083,0:03:23.720 and now located underneath Yellowstone [br]National Park in Wyoming due to the 0:03:23.720,0:03:28.873 North American plates slowly moving over[br]the stationary hot spot. 0:03:28.873,0:03:31.659 These spectacular basalt lava eruptions, 0:03:31.659,0:03:36.413 more than 300 distinct events punctuated[br]by thousands of years of quiet between 0:03:36.413,0:03:38.499 each lava flood. 0:03:38.499,0:03:44.240 Flooded and buried, the rugged inland[br]landscape of the Pacific Northwest. 0:03:44.240,0:03:49.311 Many of the biggest lava flows made it[br]from their fissures in Idaho all the way 0:03:49.311,0:03:54.137 to the towering cliffs [br]of the Oregon coast. 0:03:54.137,0:03:59.564 At Pasco Washington the stack of Columbia[br]River basalt lava flows is 16,000 ft. 0:03:59.564,0:04:02.905 thick, more then 3 miles of lava. 0:04:02.905,0:04:07.554 Sitting on top of a 17 million year old[br]landscape. 0:04:07.554,0:04:13.163 There isn't one visage to see all the[br]lava flow layers, how could you? 0:04:13.163,0:04:18.001 To truly grasp the scale of the lava stack[br]one has to visit scattered canyons that 0:04:18.001,0:04:23.256 expose a dozen flows at a time, like[br]in the Yakama River Canyon, 0:04:23.256,0:04:25.024 and the Columbia River Gorge, 0:04:25.024,0:04:27.075 or in the Grand Coulee, 0:04:27.075,0:04:31.096 which was carved just thousands of years[br]ago, not millions. 0:04:31.096,0:04:33.600 By the Ice Age floods. 0:04:33.600,0:04:42.674 [ Music Plays ] 0:04:42.674,0:04:47.128 During the Ice Age, a thick ice sheet[br]covered much of North America, 0:04:47.128,0:04:51.816 advancing and retreating in response to[br]global climate. 0:04:51.816,0:04:56.203 In Washington, Canadian ice crossed the[br]border in different places. 0:04:56.203,0:05:01.820 West of the cascade range, the Puget Lobe[br]filled the Puget Lowland with 3,000 ft. 0:05:01.820,0:05:04.373 of ice, above present day Seattle. 0:05:04.373,0:05:07.110 With enormous erratics left behind 0:05:07.110,0:05:09.778 after the ice melted back. 0:05:09.778,0:05:15.283 Most Puget Sound residents live on[br]complicated sets of Ice Age deposits. 0:05:15.283,0:05:19.803 Glacial till, glacial outwash, that[br]reveal ice on the move. 0:05:19.803,0:05:25.191 Advancing and retreating with glacial[br]licks riding the front of an active 0:05:25.191,0:05:27.743 ice margin. 0:05:27.743,0:05:32.797 East of the cascades, the Okanogan Lobe[br]crept into north central Washington. 0:05:32.797,0:05:36.452 Gorgeous glacial moraines and impressive[br]glacial erratics 0:05:36.452,0:05:41.589 have been sitting on the Waterville[br]plateau for at least 12,000 years. 0:05:41.589,0:05:46.399 During some of the Okanagan ice advances,[br]the mighty Columbia River was diverted, 0:05:46.399,0:05:49.785 and sent due south, through the Grand[br]Coulee, 0:05:49.785,0:05:52.853 and over dry falls. 0:05:52.853,0:05:57.238 In northern Idaho, the Purcell Lobe [br]combined with the rugged topography 0:05:57.238,0:06:00.667 of the Bitterroot Mountains and blocked[br]Montana's Clark Fork River, 0:06:00.667,0:06:03.820 near present day Saint Point Idaho. 0:06:03.820,0:06:10.542 Glacial Lake Missoula formed as glacial[br]melt water backed up behind the ice 0:06:10.542,0:06:15.647 dam forming a huge lake, more then 3,000[br]square miles of western Montana. 0:06:15.647,0:06:21.650 Old shorelines of the lake are visible [br]above the University of Montana. 0:06:21.650,0:06:27.438 Faint water marks first noted in 1886[br]by T.C Chamberlin. 0:06:27.438,0:06:34.595 The lake was 950 ft. deep at Missoula and[br]twice that depth in neighboring valleys. 0:06:34.595,0:06:40.983 And then it happened, Glacial Lake[br]Missoula breeched the ice dam and raged 0:06:40.983,0:06:42.883 across eastern Washington. 0:06:42.883,0:06:46.871 Through the cascade range and reached the[br]mighty Pacific Ocean. 0:06:46.871,0:06:50.156 Up to 10 cubic miles per hour. 0:06:50.156,0:06:54.378 A rate 10 times the combined flows of all[br]the rivers on planet earth, 0:06:54.378,0:06:59.733 surged through Eddy Narrows, and other[br]narrow valleys in western Montana. 0:06:59.733,0:07:05.637 When the huge lake suddenly drained,[br]giant current ripples were created 0:07:05.637,0:07:08.356 on the lake's floor. 0:07:08.356,0:07:11.224 And the failed ice dam was replaced by a[br]new one, 0:07:11.224,0:07:13.560 and another Glacial Lake Missoula formed. 0:07:13.560,0:07:16.462 Which led to the next Missoula flood. 0:07:16.462,0:07:19.964 Drama repeated many times. 0:07:19.964,0:07:24.902 Banded deposits at the bottom of Glacial[br]Lake Missoula show the lake form dozens 0:07:24.902,0:07:29.488 of times and released quickly over [br]Washington each time. 0:07:29.488,0:07:33.308 Rinse and repeat up to 100 times. 0:07:33.308,0:07:38.529 These are slack water sediments from the[br]Missoula floods. 0:07:38.529,0:07:41.332 We're in Tammany Barge of south of [br]Lewiston Idaho. 0:07:41.332,0:07:44.885 Each of these is a separate Missoula [br]flood. 0:07:44.885,0:07:50.289 We're 150 miles upstream from Wallula gap [br]that means water from Montana 0:07:50.289,0:07:56.762 made it to Wallula gap and to back up this[br]far up the snake river drainage. 0:07:56.762,0:08:02.203 This is one event, silt falling from[br]the bottom of Lake Lewis. 0:08:02.203,0:08:05.172 And another flood, and another flood. 0:08:05.172,0:08:07.273 Now that's amazing. 0:08:07.273,0:08:17.730 [ Music Plays ] 0:08:17.730,0:08:21.034 Meanwhile, another Ice Age flood, the [br]Bonneville flood, 0:08:21.034,0:08:24.119 happened around the time of Missoula[br]flooding. 0:08:24.119,0:08:28.990 Lake Bonneville, and Ice Age predecessor[br]to the Great Salt Lake. 0:08:28.990,0:08:32.876 Filled and spilled out of Utah and into[br]southern Idaho. 0:08:32.876,0:08:35.745 The old shorelines of Lake Bonneville, 0:08:35.745,0:08:40.166 ancient bathtub rings above Salt Lake[br]city were first described by G.K Gilbert 0:08:40.166,0:08:42.735 in 1890. 0:08:42.735,0:08:45.288 A desert under water. 0:08:45.288,0:08:51.077 Once the Bonneville basin was filled to[br]capacity, 17,400 years ago. 0:08:51.077,0:08:56.013 The erosion of loose rocky material at[br]Red Rock Pass led to the rapid 0:08:56.013,0:08:57.953 lowering of Lake Bonneville, 0:08:57.953,0:09:03.856 and the Bonneville flood surged north[br]into Idaho snake river plane. 0:09:03.856,0:09:06.827 Unlike the Missoula floods and it's ice[br]dam, 0:09:06.827,0:09:10.796 the Bonneville flood involved a lot more[br]water then the biggest Missoula flood. 0:09:10.796,0:09:12.697 Probably about twice as much water. 0:09:12.697,0:09:16.502 But the constriction at Red Rock Pass that[br]had spilled out through 0:09:16.502,0:09:21.005 was much smaller then where the ice bridge[br]was breached in northern Idaho. 0:09:21.005,0:09:24.142 The Bonneville water came out slower. 0:09:24.142,0:09:28.628 So while the volume of Bonneville water[br]was twice as large as the largest Missoula 0:09:28.628,0:09:34.200 flood, the peak discharge was only[br]about 1/10 of the largest Missoula flood. 0:09:34.200,0:09:36.952 Each Missoula flood lasted for days. 0:09:36.952,0:09:40.704 The Bonneville flood lasted for weeks. 0:09:40.704,0:09:43.857 Gorgeous deposit. 0:09:43.857,0:09:46.792 All these rocks were deposited by the[br]Bonneville flood, 0:09:46.792,0:09:47.960 just one flood, right? 0:09:47.960,0:09:50.813 Just a few weeks all these rocks were[br]dropped. 0:09:50.813,0:09:54.799 17,400 years ago. 0:09:54.799,0:09:58.452 Sitting on top are Missoula flood[br]sediment, 0:09:58.452,0:10:02.556 there are 20 different Missoula food[br]layers here. 0:10:02.556,0:10:11.813 So at this spot, we had 20 Missoula floods[br]after the Bonneville flood. 0:10:11.813,0:10:14.165 So how do we know this stuff? 0:10:14.165,0:10:16.466 Carefully crafted geographic maps, 0:10:16.466,0:10:19.802 made in the field by generations of[br]geologists have measured both the 0:10:19.802,0:10:22.522 erosional chasms cut by the floods 0:10:22.522,0:10:26.359 and have catalogued piles of rocks and[br]layers of sediment that the floods have 0:10:26.359,0:10:28.861 left behind. 0:10:28.861,0:10:33.246 Water is scarce here in eastern [br]Washington today, it's a desert. 0:10:33.246,0:10:37.617 But the landscape has a strong stamp of [br]water, and lots of it. 0:10:37.617,0:10:41.689 The Ice Age floods tore up the crust,[br]revealing the Columbia River salt lavas 0:10:41.689,0:10:44.642 that flowed millions of years earlier. 0:10:44.642,0:10:49.044 Leaving dramatic landmarks like the Grand[br]Coulee, Dry Falls, the crisscrossing 0:10:49.044,0:10:51.930 flood paths of Drumheller Channels, 0:10:51.930,0:10:53.831 and Palouse Falls. 0:10:53.831,0:10:56.550 Tons of bedrock were hauled away by the[br]floods, 0:10:56.550,0:11:00.937 as the water exploited deep cracks in[br]the bedrock. 0:11:00.937,0:11:04.723 Box shaped valleys called Coulees formed, 0:11:04.723,0:11:07.942 where the most aggressive water did the[br]most digging. 0:11:07.942,0:11:12.529 Rock precut and hauled off by the flood[br]water cruising at more then 60 mph 0:11:12.529,0:11:14.914 in places. 0:11:14.914,0:11:21.137 And there are amazing potholes drilled by[br]the swirling dynamics of floodwater. 0:11:21.137,0:11:26.290 Often revealed in the vertical Coulee[br]walls, cut by the erosive ice age floods. 0:11:26.290,0:11:29.861 Lost worlds hidden in the salt bedrock. 0:11:29.861,0:11:35.613 At the bottom of key lava flows, pillow[br]structures where lava battled lake water, 0:11:35.613,0:11:40.853 and petrified logs, provide detailed clues[br]to the ancient forests and lakes that 0:11:40.853,0:11:44.890 thrived in eastern Washington, during[br]the thousands of years between 0:11:44.890,0:11:49.742 devastating lava floods that repeatedly [br]buried vibrant thriving ecosystems 0:11:49.742,0:11:51.578 in thick lava. 0:11:51.578,0:11:55.648 A landscape full of life, with each lava[br]burial creating a lifeless, 0:11:55.648,0:12:00.552 featureless, moonscape. 0:12:00.552,0:12:05.889 Millions of years later, each of the 100[br]floods made it to the Pacific Ocean, 0:12:05.889,0:12:08.576 but does that mean that each flood[br]maintained 0:12:08.576,0:12:11.461 a high speed for Montana to the Coast? 0:12:11.461,0:12:17.099 No, like today there are many obstacles[br]to negotiate on a journey from the 0:12:17.099,0:12:20.102 Rocky's to the Pacific Ocean. 0:12:20.102,0:12:23.488 The Ice Age floods had the same [br]roadblocks. 0:12:23.488,0:12:27.324 Wallula Gap, eastern gateway to the[br]Columbia River gorge was a bottleneck 0:12:27.324,0:12:28.324 for the floods. 0:12:28.324,0:12:32.361 Every drop of Ice Age flood water needed[br]to squeeze through the gap, 0:12:32.361,0:12:35.964 which was the secret passage through[br]the cascades, 0:12:35.964,0:12:38.766 and onto the Pacific. 0:12:38.766,0:12:44.287 At Wallula Gap, flood water waiting to[br]enter became Lake Lewis. 0:12:44.287,0:12:47.675 The bigger the flood, the larger the[br]Lake Lewis. 0:12:47.675,0:12:51.395 Calm and dirt brown with suspended loose, 0:12:51.395,0:12:53.962 which crept up neighboring river valleys. 0:12:53.962,0:13:01.185 The Yakama river, the Walla Walla River, [br]and the Snake River. 0:13:01.185,0:13:05.039 The water of Lake Lewis must have gotten[br]clear with each passing day. 0:13:05.039,0:13:09.841 The fine grain material falling out of the[br]lake and onto the lake bottom, 0:13:09.841,0:13:10.977 the result? 0:13:10.977,0:13:13.678 Impressive layers of slack water sediment. 0:13:13.678,0:13:16.114 Each layer from each Lake Lewis. 0:13:16.114,0:13:20.233 And the surface of Lake Lewis was[br]full of icebergs. 0:13:20.233,0:13:22.120 How do we know that? 0:13:22.120,0:13:26.440 There are large erratics all across [br]central Washington that mark spots where 0:13:26.440,0:13:29.826 the icebergs drifted to the edge of the [br]lake. 0:13:29.826,0:13:35.463 Upstream some of the largest Missoula[br]floods came down of Columbia River 0:13:35.463,0:13:37.300 over Wenatchee. 0:13:37.300,0:13:41.952 And downstream Wenatchee, West bar is a [br]classic location to ponder the speed 0:13:41.952,0:13:46.122 and depth of the floods. 0:13:46.122,0:13:51.425 You old enough to remember the media [br]frenzy over Evil Kneviel daredevil jump 0:13:51.425,0:13:54.395 over the Snake River Canyon? 0:13:54.395,0:13:56.747 That's the canyon that the Bonneville[br]flood, 0:13:56.747,0:13:59.251 the one from Utah flowed through,[br]remember? 0:13:59.251,0:14:03.303 Lake Bonneville spilling over Red Rock[br]Pass and into the Snake River drainage 0:14:03.303,0:14:05.639 of Southern Idaho. 0:14:05.639,0:14:10.793 The floods scoured canyon walls[br]and gouged holes in the canyon floor. 0:14:10.793,0:14:14.161 Creating Shoshone Falls and Twin Falls. 0:14:14.161,0:14:16.698 The water ripping through the narrow[br]regions of the canyon, 0:14:16.698,0:14:20.835 dislodging the salt boulders, and[br]tumbling them down stream. 0:14:20.835,0:14:22.969 Where the flood channel widened, 0:14:22.969,0:14:27.024 the boulders were heaped into[br]impressive piles. 0:14:27.024,0:14:29.892 The Bonneville flood then entered Hells[br]Canyon, 0:14:29.892,0:14:31.775 the deepest canyon in North America, 0:14:31.775,0:14:35.514 before joining the channeled scab lands[br]of eastern Washington. 0:14:35.514,0:14:39.633 The deposits left by the flood give us[br]reach detail. 0:14:39.633,0:14:45.004 Giant flood bars, more then 100 ft. [br]above todays Snake River, 0:14:45.004,0:14:50.458 sit in narrow stretches of Hells Canyon,[br]showing us where the flood got choked up. 0:14:50.458,0:14:54.678 Creating flood stages hundreds of feet[br]feet high behind it. 0:14:54.678,0:14:59.383 In shlock water sediments are found all[br]through the Bonneville flood route, 0:14:59.383,0:15:02.601 but not the repetitive shlock water [br]sediments, like the Missoula Floods, 0:15:02.601,0:15:08.673 remember, there was just one Bonneville[br]flood. 0:15:08.673,0:15:13.077 All told, 100 different layers of shlock[br]water sediment have been documented 0:15:13.077,0:15:14.863 in eastern Washington. 0:15:14.863,0:15:18.448 100 Missoula floods! 0:15:18.448,0:15:23.002 But there is work yet to be done. 0:15:23.002,0:15:25.623 What's the age of each flood? 0:15:25.623,0:15:29.307 Is a more complete record of the Ice Age[br]flood sitting in the Pacific Ocean at the 0:15:29.307,0:15:31.742 mouth of the Columbia River? 0:15:31.742,0:15:36.663 And with the floods of lava, why did such[br]pure oceanic lava flood a 0:15:36.663,0:15:39.466 continental scene? 0:15:39.466,0:15:43.536 And how did the lava stay molten for 300[br]miles? 0:15:43.536,0:15:46.189 Much yet to be determined. 0:15:46.189,0:15:50.072 With our huge floods, in the Pacific[br]Northwest. 0:15:53.182,0:16:18.000 [ Outro Music Plays ]