After passing through Sentinel Gap on our Saturday drive, I arbitrarily picked a side road and headed west toward the Columbia to see if I could get a different perspective of the Gap. The road ended up at a small boat ramp on a backwater pond near the river. The sun was just about ready to drop behind Umptanum Ridge. The late afternoon created a beautiful glow on the grasses and winter tree trunks. As a little bonus, I was able to get a piece fo the western ridge of Sentinal Gap in my image. For reference, the height of the water in the Columbia River approached the top of this ridge during the Missoula Floods. The area where I was standing when taking this image was at the bottom of Ice Age Lake Lewis. The water would have been several hundred feet above my head during the floods.
Yesterday was a beautiful winter day here in Central Washington. I woke up with a desire to get out and do a little exploring. Mary and I hopped into our car and decided to wander through part of the path of the Ice Age floods. The landscape in Eastern Washington is amazing. Understanding how the different formations were created takes a lot of imagination.
The basalt bluffs across the valley are about 150-200 feet high. Imagine a wall of water 100 to 200 feet higher than the bluffs rushing and swirling through this channel at 50 plus miles per hour. The water swirls as eddies carve out “pot holes” like maybe what the small lake covers. The turbulent waters gouge through the basalt, picking up and carrying the rock out of the channel.
Memorial Day was a beautiful Spring day! We woke up to a beautiful morning full of sunshine. It was time for a road trip! We decided to drive to the Palouse and visit Palouse Falls. Three hours later we were waiting in line to enter the Palouse Falls State Park. Many others had the same idea as we did. The drive and wait were worth it.
This image is taken from above the Palouse River just below the Palouse Falls. Recent rain created the green foliage on the plateau and canyon walls. Normally the scenery is pretty brown. The sky was covered by a patchwork of puffy white clouds. The scene was a a gift!
Can you imagine these falls during the Ice Age Missoula Floods? Water was rushing over the top flat rim of the plateau at 70 miles per hour! The existing falls is but a small trickle of what was.
The amazing geological history of Eastern Washington continues to fascinate me. The current falls are 187 feet tall. The Ice Age Flood falls were about twice in height. Basalt on the canyon walls was created by a series of lava flows between 15 & 18 million years ago. The Missoula Floods creating the canyon occurred 12 to 15 thousand years ago (just a spec of time in our geologic history).
Argillite Boulder – Rattlesnake Mountain, Washington
This image depicts an interesting perspective of time. The rock in the foreground was deposited here on Rattlesnake Mountain around 15,000 years ago. The Rattlesnake Mountain and the Horse Heaven Hills in the background were created as part of the Yakima Fold formation about 1.5 million years ago. The bedrock of this area is basalt from basalt flows through eastern Washington from 6-15 million years ago. The argillite boulder in the foreground is metamorphic rock from western Montana formed 1.5 billion years ago.
So here I was, sitting on a rock created before life on earth existed, brought here by a humongous flood around 15 thousand years ago, deposited on mountains uplifted 1.5 million years ago, created by a series of gigantic lava flows about 2 miles thick 6-15 million years ago. And I think I am old at 67 years. As many of my Whizzy friends would say, “It’s a thinker.”
Granite Erratic – Rattlesnake Mountain, Washington
The Missoula Floods carried large icebergs from the glaciers that dammed Lake Missoula or from the Okanagan lobe glacier that dammed Lake Columbia along with them as they made their way to the Pacific. As the icebergs melted or became “stranded” against ridges that formed Lake Lewis, they dropped the rocks that the glaciers picked up as they scoured their paths southward. Granite is present in Montana as well as northern Washington. But it is not present in central Washington. The origin of this single granite erratic on Rattlesnake Mountain is therefore not definite. It could have come from either Montana or northern Washington.
This chunk of granite is approximately 6′ in length. It is located at about 800 feet elevation (my estimate).
It is hard to comprehend how enormous the Missoula Ice Age Floods were. The edge of the bluff in the top left hand corner is approximately 200 feet high. The water level during the Missoula Floods was about 200 feet above the top of the mesa. The distance across the Drumheller Channels was 8-11 miles wide. The water is estimated to have moved through here at 50+ miles/hour. The landscape left behind is amazing. My mind wanders about contemplating what it must have been like.
This image was taken at the overlook off the main road running through the reserve.
Rattlesnake Ridge and Pasco Basin from Saddle Mountain, Washington
This image was taken from the top of Saddle Mountain looking southwest toward Rattlesnake Ridge. During the Missoula Floods, the water level of Lake Lewis between these two ridges was about 600 feet above the current basin floor.
As I was photographing on top of the mountain, I felt a cold wind pick up. The skies turned dark and I could see the rain coming toward me. I decided it was a good time to pack up my gear and head down the steep gravel/dirt road before it turned to mud. It was the end of a good day and a great trip driving around the Pasco basin exploring for traces of the Ice Age floods.
This image was taken north of Sentinel Gap, looking south. The Columbia River is barely visible in the center of the photo. During the Ice Age Missoula Floods, Crab Creek thundered through here joining the Columbia River. This was the western path for the waters rushing through Drumheller Channels as it was diverted by the Saddle Mountains. The small rocks in the foreground are likely to have been carried by the rush of water as it carved out the scablands through the Drumheller Channels.
This image was taken looking north through Sentinel Gap. This gap cuts through the Saddle Mountains which separate the Pasco and Othello basins in Eastern Washington. The Columbia River runs through this gap on its way to the Oregon/Washington border. At the time of the Missoula Floods, the water level going through the gap reached the top of the left ridge, flowing into Lake Lewis which covered the Pasco basin.
The erratics in the foreground most likely are from the gap, carved away by the raging wall of water that flowed through it.