A tour of the Ice Age Floods in Washington

[Occidental]

We took about ten day to see several of the geological features scattered around eastern Washington that all add up to a tour of the after effects of the massive ice age floods that were released from lake Missoula during the last ice age.

Part one is now complete and posted to the blog: Touring the Ice Age Floods of Washington, Part 1 – Occidentalist

as well as part 2: Touring the Ice Age Floods of Washington, Part 2 – Occidentalist

Stops include Palouse Falls, the Wallula Gap, Hanford Reach, Ginko Petrified Forest State Park, Frenchman Coulee, Potholes Coulee, Drumheller Channels, and the Columbia National Wildlife Refuge for part 1.

Stops for part two include the Ephrata Fan, Dry Falls, Grand Coulee, Steamboat Rock, Twin Lakes and Rock Creek.

 

[Wandering Sagebrush]

Ed, I really enjoyed your TR! Thanks!

 

[AWG_Pics]

Wow! We are planning a similar voyage of discovery. My wife grew up on Crab Creek about halfway between Drumheller Channels and the Ginko Petrified Forest. We are very much looking forward to watching your YouTube together. More feedback soon!

 

[h2opup]

Wow! What a fantastic teaser photo. Looking forward to reading your blog in it's entirety and to seeing these sites in person. Thanks for the report!

 

[buckland]

As always Ed ...a fabulous TR ...really enjoyed the video.

 

[rjap]

Been to a few of those places. Neat idea to connect them up in a tour. The Palouse is kind of scenic in its own way.

 

[AWG_Pics]

We watched your excellent video last night. You hit plenty of the best points of interest of the channeled scablands. One interesting note is when you were on steamboat rock the plants found there are unique in some ways, having never been grazed by cattle or sheep.

Here is a fun photo from inside Wells Dam:

Inside most of the dams on the Columbia there are odd, sometimes monumental art works.

Thanks for the trip report!

 

[Occidental]

Part 2 of the trip report is complete and posted: Touring the Ice Age Floods of Washington, Part 2 – Occidentalist

Thanks all for the comments, I appreciate them.

 

[Occidental]

We watched your excellent video last night. You hit plenty of the best points of interest of the channeled scablands. One interesting note is when you were on steamboat rock the plants found there are unique in some ways, having never been grazed by cattle or sheep.

Here is a fun photo from inside Wells Dam:

Inside most of the dams on the Columbia there are odd, sometimes monumental art works.

Thanks for the trip report!

The grasslands at the top of Steamboat Rock did seem to be fairly intact. We did note lots of hoof prints, we presumed from deer, up there, which was a bit of a surprise since we didn't note any water, and it's not too easy to get up and down in most places. Perhaps there are a few pools here and there that get filled with rain.

 

[AWG_Pics]

The grasslands at the top of Steamboat Rock did seem to be fairly intact. We did note lots of hoof prints, we presumed from deer, up there, which was a bit of a surprise since we didn't note any water, and it's not too easy to get up and down in most places. Perhaps there are a few pools here and there that get filled with rain.

I have seen 1 mule deer up on top some years ago.

 

[Casa Escarlata Robles Too]

Ed thanks for the great trip. That is some very interesting country.
Frank

 

[Vic Harder]

Awesome TR. Regarding Steamboat rock (or any of those exposed Basalt Columns): The Loess (150' you said) was eroded away, and how much of the basalt was eroded away from on TOP of the basalt columns? You said the flows were 2.5 miles thick.... how thick are they now? Just trying to comprehend the majesty and power of water boggles the brain.

 

[Occidental]

Awesome TR. Regarding Steamboat rock (or any of those exposed Basalt Columns): The Loess (150' you said) was eroded away, and how much of the basalt was eroded away from on TOP of the basalt columns? You said the flows were 2.5 miles thick.... how thick are they now? Just trying to comprehend the majesty and power of water boggles the brain.

Great question. From what I understand, the top of the coulees and surrounding areas that are mainly farm and rangeland are still essentially the top of the flows. In the deepest areas they are estimated to be 2.5 miles thick. Think of them essentially flowing like water and filling in the topography at the time. So valleys and depressions would have deeper flows than mountainous areas. The Columbia river flows essentially created a multilayers cake of basalt that filled in a pool from the Idaho border, into Washington and eastern Oregon.

The Grand Coulee is about 1300 feet deep, and that is the deepest of the coulees if I understand correctly. So the floods eroded away up to 1300 feet of that basalt that formed as multiple layers. The width and length is much more expansive. From what I have read, Dry Falls was a headcut waterfall that was 20 miles in length, and 1.5 miles wide at the last flood event.

I will attach a couple graphics that help with the depth and extent a bit.

 

[Vic Harder]

wow. Any clue as to the source of the flows? (I could probably look that up online....)

Yup.. Same hotspot as Yellowstone.

Columbia River Basalt Group Stretches from Oregon to Idaho

The Columbia River Basalt Group (CRBG) is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over 210,000 km2 of mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada.

www.usgs.gov

And this is considered to be a SMALL flow.

 

[Wandering Sagebrush]

Another bit of info.

USGS Volcanoes

 

[AWG_Pics]

wow. Any clue as to the source of the flows? (I could probably look that up online....)

Yup.. Same hotspot as Yellowstone.

Columbia River Basalt Group Stretches from Oregon to Idaho

The Columbia River Basalt Group (CRBG) is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over 210,000 km2 of mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada.

www.usgs.gov

And this is considered to be a SMALL flow.

Hi Vic
Not sure if you meant the water flows or the lava flows. Either way this site will give you all you need to know and then some:

CWU Geological Sciences - Ice Age Floods

Down at the bottom of this list of papers and posters is a paper by Kasbohm (2023) with a discussion of the eruptive history of the basalt lavas. Elsewhere in the list is a list of papers about the ice age floods.

Here is a link to a bunch of videos on the same topic: Nick Zentner

The papers and the videos go hand in hand.

Have fun. It took me about a year to read most of this.

Tony

 

[SlowernOlder]

Very nice report, thank you.

 

[Casa Escarlata Robles Too]

There is so much info you can just go down any rabbit hole and not come up for air fro a long time.
Thanks for all the info.
Frank

 

[ski3pin]

We love going down rabbit holes and we both - I read it aloud to Julie as we're holed up due to weather - your excellent trip report! We can't wait for a chance to watch your video, after we return home. Thank you!

 

[Taku]

Nice trip report! And as you drive along Highway 200 and I-90 heading to or from Missoula, there are signs of the flood events well documented in the Roadside Geology guide for Montana. Along the rivers there are large deposits of sands and gravels well above the current river levels in very large eddies from the floods. And in Missoula numerous shorelines are evident on Mounts Jumbo and Sentinel above town. Pretty amazing floods!