"Slip Slidin' Away": The 1993 Bliss Landslide, a dramatic earthflow that diverted the Snake River

On July 24, 1993: a 100-acre (0.4 sq km) swath of land failed and slid into the Snake River, temporarily blocking it and permanently diverting it southward. Travel to the scene of this recent geologic event with geology professor Shawn Willsey. Take in the entirety of the "Bliss Landslide" (actually an earthflow) from the south before journeying out to the margin of the slide to examine the material that failed. Finally, head down to the toe of the slide to investigate the 50,000 year old lava dam and pillow lava that tie into the story. You can learn more about this site in my book, Geology Underfoot in Southern Idaho. Signed copies available here: shawn-willsey.square.site/
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Shawn Willsey
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Twin Falls, ID 83303
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[@shawnwillsey]

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[@YouHaveNoCtrl]

I remember the night this happened. I was working for a farming operation and we were trying to get some hay equipment across the bridge and up to some fields above Bell Rapids. Some guys in the leading tractors radioed and thought they took a wrong turn because the road ended. Boss drove down and found the road cut away. I didn't see it until the next evening and by then the river had broken through so I missed it backing up. There were some outbuildings on the slide and I remember how distorted and bent they looked after being 'relocated'.

[@annej.7125]

Crazy

[@jakegroat4447]

I used to work on the wind farms near Bliss. I've driven over that slide many times, noticing the dramatic change in soil. But I didn't know what the cause was. Now it all makes perfect sense. Thanks for posting.

[@CowboyDave1812]

I grew up just a few miles from this place back in the 1960's and 70's. The geology of the area was always of interest to me, but not enough to make a career of it. I greatly appreciate these videos and the stories.

[@EricFielding]

Great job explaining how the 1993 landslide was related to the old lava dam from 50,000 years ago.

[@SueFerreira75]

Thank you, Shawn. Love your videos and explanations of the geology .

[@gigistrus490]

How lucky I am this information is available and someone freely shares their knowledge.

[@davidk7324]

Great video. If I were a younger man, I'd want to take some classes from you! You are a very effective communicator and teacher.

[@shawnwillsey]

Wow, thanks!

[@alexneria6677]

I often fish the powerplant reservoir downstream of this site. I have always been fascinated by the basalt formations on the upper end of the "reservoir" where it turns back into river. Because of your video I now have a new understanding of one of my favorite fishing holes. Very informative.

[@jamiewilson8338]

I love all of the "Roadside Geology" book's! The Nick Zentner UTUBE series are fun and "classy", his original OPB "3Minute Geology", got me hooked on Geology. Thanks for this awesome informative & fascinating video.

[@GunsandCoasters]

1993 was a wet year. There's an understatement. A lot of flooding on the Missouri River that year. Bridges needed repair work because the water washed away so much material around the support columns.

[@timpointing]

@GunsandCoasters I had a quick look at the precipitation data for the area (he best I was able to come up with were the data for Boise.) Jan through Jul got almost 50% more than normal (10.7" vs 7.4"), with Jun and Jul each recorded more than double the normal rainfall. So, yeah, it was WET! ⛈🌧⛈🌧

[@richavic4520]

@@GunsandCoasters Coincidentally, I'm installing relief wells on the Kansas River upstream from the confluence with the Missouri River. The project is the levee raise that is the product of 1993's flooding.

[@Anne5440_]

In '93 I was living in Central Kansas. I vaguely remember hearing when this slide occurred. Of course, we didn't get details back there. In the 70s there was a perhaps similar slide on the Yakima river in the canyon between Ellensburg and Cle Elum WA. I noticed the Snake there looked like a fun rapids to run. In the 70s and 80s we were doing white water canoeing. We mostly would run class 2 rivers that had occasional class 3 rapids. So I was side tracked by the water a bit before you talked about it. Of course the Snake river is at that point about twice the size of the upper Yakima river. I found the story of the Bliss slide very interesting. I also liked how much you showed us about the pillow lava. The first place I saw pillow and aa lava was at craters of the moon. Now I need to put videos away and read some more in my plate tectonics book. This 2 weeks break is study time to wrap my brain around Baja/ BC.

[@ldahospud]

Absolutely fascinating, and your explanations and diagrams really helped me understand what happened at Bliss. I have Roadside Geology of Idaho but I’ll order your book too-I didn’t know about it until now.

[@rachaelb9164]

OMG we were literally just there a little over a week ago. We stayed at an AirBNB in Hagerman and crossed that bridge a couple times. I wish I would have seen this video before our trip. Beautiful area with a fascinating geological history. Will have to go again when it’s warm enough to rockhound.

[@alelsayed9465]

Thanks Shawn for an excellent presentation. I noticed the pattern of cracks in the road pavement @ 10:57 possibly indicative of subsoil creep.

[@Gizathecat2]

Thank God this slide was in “the middle of nowhere” unlike the Oso slide in Snohomish County, WA. I remember the Oso slide very well. The search and rescue/recovery helicopters flew over my house for days!

[@charliewatts6895]

Here in Eastern Ontario, Canada we have what are called Leda clays or rock flour produced by the glaciers, and then settling out in glacial lakes tens of thousands of years ago. This clays cause instability in slopes and landslides.

[@johnbollenbacher6715]

I love how the story all ties together.

[@vhhawk]

Never knew of this one. Thanks for the tour. A good day to learn. 16:15 diagram for those who need it

[@shawnwillsey]

Glad it was helpful!

[@daveh893]

Fascinating story of the history of that part of Idaho. You are lucky to have to much geology in that area. Here in northern Illinois not so much!

[@lukemorrison8376]

I was 14 the year this happened, my Mom taught in Bliss most of her career. The slide was definitely interesting to see back then.

[@primateinterfacetechnologi6220]

Excellent summary of the events leading up to what we observe today in this spot... And that river sure does look like it's full of trout. If I recall correctly the snake River has cutthroat trout... My favorite trout that I've never caught. Probably non-native Browns and Rainbows too. I grew up on the coast of California where it's rainbow trout until you're just bored catching them... A friend of mine even caught one in the ocean while fishing for salmon. Yay! peace.

[@pd6921]

You gave a very clear and informative presentation on the slide. I found it very interesting. Thank you for taking the time to make it. I plan to check into your other videos.

[@shawnwillsey]

Glad you enjoyed it!

[@ped832]

Wow, another fine lesson. I should remember this event from the news at the time, but I don't. Keep up the great work.

[@Danika_Nadzan]

Thanks for another fascinating field trip! As always, the diagrams perfectly sum up your excellent explanations.👍🏻👍🏻

[@shawnwillsey]

Thanks again!

[@ken2tou]

Thanks Shawn! The geology of Idaho is quite fascinating!

[@billrobbins5874]

First time hearing of this. Fascinating.

[@mikekilian5403]

Very interesting Shawn. Love the drawings and explanations.

[@shawnwillsey]

Glad you enjoyed it

[@timpointing]

Agreed. The diagrams, both from the book and the Sharpie one, are clear and understandable!

[@jkgardner1933]

Shawn, great work on explaining this event. Long time Nick fan, and have been enjoying your productions the last year. Keep up the great work.

[@shawnwillsey]

Awesome. Thanks for watching and learning with me.

[@claytonmehring]

Fantastic video. You’re ability to describe geologic information, in an easily digestible way, makes these videos must watch for anyone who lives in Idaho or is interested in Geology. Great job!

[@shawnwillsey]

Wow, thank you!

[@timpointing]

And also for people who are not in Idaho nor particularly specifically interested in geology. As long as you have a thirst for knowledge, Shawn Willsey is here to quench that thirst! 👍

[@hebneh]

There are excellent videos of lava entering the ocean in Hawaii, and underwater, you can see the progress and formation of pillow lava. You can also see the explosive interactions that can result in black sand, which would be comparable somewhat to the fragmented rock chunks seen here among the pillow lava along the river.

[@joemeslovich1595]

My 10 year old daughter watched this video with me and thinks you sound like Owen Wilson's character Lightning McQueen 🤣.

[@shawnwillsey]

"Kachow!"

[@ped832]

And we all know water will go around, over, under or through. Your comment on the argicultural irrigation perhaps loosening the soils answered a question I hadn't asked yet.

[@stevekolstad4445]

I have your book and I read about this slide in your book. Your video really helped me understand the slide

[@dabonemarrow5337]

Thank you, it seems it is a very interesting slide!! Keep doing what your doing. You do it well!! Godsppeed

[@rodhoskin8238]

I remamber hearing on the news about this and sometime after it happenend we drove down to see it, Some people were rafting that day and they had just passed that area when the slide happened and watched it come down just behind them. A little past where he had crossed the road to the yahoo clay the road he is standing on goes down the grade then splits to the left to go upstream and right to go to the bridge, where a nice white two story cottage was surrounded by trees. The slide itself did not hit the house but caused the ground under the house to move and distorted the house considerably. It looked like something you would see in a Dr. Seuss book, They eventually tore it down. Upstream on the Bliss grade road on the North side is a small stream that travels toward the bridge and cuts under the road. I trim trees for Idaho Power lines and have to go up that stream a small way. In doing so I saw some rounded lava rock and some of it had small creek gravel stuck on it. I tried to pick some of it off with my fingernails and only got a couple small pieces to come off but could not figure out how and why some one would glue them on there. Years later I read his book "Geology underfoot" where he explains more about Pillow lava formation where the lava flows into a stream onto the gravel underwater and fuses the gravel onto the lava. Later floods expose the formation. Both of his books answer a lot of questions. Well worth the read.

[@ericsarnoski6278]

A wetter than normal year would lead me to speculate that it was probably hydraulic pressure that caused the collapse. Farm irrigation on the top had already saturated the soil over time. Add a little extra rain and the displacement would lift up the soil. I Enjoy your videos.

[@annehopkins3393]

Thanks for another fabulous field trip. You pack so much information and fascinating visuals into these videos.

[@nitawynn9538]

I wondered how you would tie it all together. You did it beautifully and it all made sense. Thanks!

[@maryt2887]

Great video. Love the connections between ancient and recent events and the diagrams showing the process. I went to Google Earth and checked the Timeline as you suggested to another viewer. Although the resolution was blurry, I could see the landslide come down covering the river and then the river breaking through. Awesome!

[@timpointing]

Another field trip with @shawnwillsey, another day of interesting knowledge gained!. Thanks.

[@evelyne7071]

It’s impressive, and even better to have you explain it in interesting ways.

[@sharonseal9150]

Thank you once again for another well done and informative video! This one helped me immensely in understanding more about the slide that I live on near Wenatchee, specifically the Malaga/Stemilt slide. We have all the same features: slide is on the outer (west) side of the bend of the Columbia, rolling clay hills interspersed here in part of the area (time formed unknown to me) at the edge of the 17 MYA Grande Ronde CRB. The slide dammed the Columbia then broke through creating Rock Island Rapids 20,000 years ago at the end of the last ice age, so extra water. Beside the 17 MYA CRB we have some 48 MYA vulcanism going on above Wenatchee at Saddle Rock near the Lovitt mine and Asamera gold mine.

[@earlysda]

Noah's global flood caused a lot of that.

[@julescaru8591]

Thanks for another field trip, I’m really enjoying these videos!

[@rogercotman1314]

Thanks again Shawn for another educational video. Thanks for the additional information on Pillow lavas and Lava dams. I think, I am observing Pillow lavas in Lake Mead Recreational Area. More investigations for me.

[@cowboygeologist7772]

If someone hadn't sent me a link saying listen how many times this guy says actually, I would have missed this video - lol. Great job; thanks for posting. I enjoyed watching.

[@davitm1]

Really enjoy watching your videos. I've recently developed a considerable interest in geology. And, as a resident of Montana, I'm particularly interested in the varied geology of the northwestern states. Comments - given the explanation of the clay deposition being formed in lake Bliss one would expect then, that the Yahoo clay formation is not at all found downstream from the lava dam. Is there any indication as to the height of the dam? How far up on the side slopes of the canyon is the clay layer (as initially deposited)? Thanks!

[@shawnwillsey]

Glad you liked these. Thanks for watching. Correct, no Yahoo Clay below lava dam. THe Yahoo Clay extends most of the way up the canyon to an elevation of about 3,180 feet. You can see it as the light colored material on Google Earth going up the Bliss Grade.

[@TerryBollinger]

A fascinating and nicely analytical video, thanks!

[@NondescriptMammal]

Very cool, reminds me of Quake Lake in Montana, the only lake that I ever swam in that was younger than me that was formed by natural processes.

[@terrycolberg6543]

Shawn, I certainly did enjoy this video. Thanks very much.

[@jdean1851]

Great Video! Thanks 4 Posting!

[@juliamarple3785]

That's cool! If you were just walking along on the other side of the river, you could tell it was a landslide. Eew slimy clay. Great video.

[@guy1137]

Super good and well understood presentation. Thanks

[@sheilatruax6172]

I love your sense of humour! It's great! Professor, you're so much fun, as well as educational.

[@shawnwillsey]

Thanks! 😃

[@vetricara1149]

Excellent Shawn

[@remorrey]

So well done!

[@sebastianbache8862]

Excellent report!

[@muhammadfahim3736]

Very simple and precise explanation.

[@shawnwillsey]

Glad it was helpful!

[@arthurma8072]

Thanks . As always. Another great geology lesson. In our world . Super

[@roadtechatlarge891]

First time your channel has been recommended to me on you tube, you’ve earned a new subscriber.

[@shawnwillsey]

Welcome aboard and enjoy the existing videos while I prepare new ones in the coming weeks. Thanks for subscribing!

[@nitahill6951]

Interest9ng and informative as usual!

[@BillyBoulder]

Great work… again. Thanks.

[@lynnlubben8750]

Very good presentation.

[@donreed]

"Geology Overhead" is a best seller in Hades.

[@MrFmiller]

Another great informative video.

[@nickmcgarvey6463]

Can't tell you how many times I've driven right over that slide and up/down the Bliss grade when I'm out fishing. I had no idea.

[@richardwest9054]

I love the diagrams, very helpful.

[@hestheMaster]

Absolutely fascinating jaunt into the past and distant past to explain why a landslide happened here and nowhere else like this in the Snake River area through Idaho. Loved the diagrams! My only question is it possible that in the future that another slide could occur on either side of this one?

[@shawnwillsey]

Absolutely, there are numerous slides along the Snake River here and south toward Hagerman. The Yahoo Clay and Glenns Ferry Formation are ubiquitous as two clay-rich lake deposits and have triggered multiple slides.

[@brookeshaffer4377]

Interesting🌟Thanks Shawn

[@freedomthroughspirit]

All new to me, thank you, very interesting and well explained.

[@shawnwillsey]

Glad you enjoyed it!

[@kevindorland738]

Thank you Professor

[@danadamson449]

There was a big pond at the top of the Slide, before it happened, just below the town of Bliss. My Dad lived in HagerMan.

[@dougbotimer8005]

Been almost 30 years, but if memory serves we were visiting family in Twin when this happened. I recall there was a party rafting near by that had a narrow escape when the slide occurred.

[@AKUSUXs]

Another great vid. I just don't remember this happening but I might have been on a 2 week Army Reserves training.

[@xcrockery8080]

That was great, what a story!

[@SandersonPhotoArt]

Well presented and understandable story. Thanks

[@shawnwillsey]

Glad you enjoyed it!

[@grauergerald9971]

Excellent ! Thanks

[@rogerdudra178]

Greetings from the BIG SKY. Good work.

[@shawnwillsey]

Hey, thanks

[@mistypuffs]

Really interesting, thank you ^^

[@randallgd]

Thank you!!

[@bwc1007]

Good stuff!

[@johnagazim4199]

Have you done a video or would you consider doing one on the Heart Mountain Detachment ? Believe your observations of the event would prove quite interesting. Thank you Shawn.

[@shawnwillsey]

Great suggestion!

[@Rachel.4644]

This adds a lot to my visit of last spring (with the Roadside Guide). Thank you Shawn. How do clay and mudstone differ?

[@shawnwillsey]

Clay is the finest sediment size but it is largely unconsolidated. Mudstone contains both silt and clay sized particles and is consolidated into “rock”.

[@randyedgar4020]

I use to run that stretch of river the bridge going over the snake use to be 50 plus feet above the river. Now it's 12 feet from all the material that came doun

[@dalehunt1383]

I remember this but never traveled to visit the area even though I live in Idaho. It would have been cool to have seen the river cut its new basin.

[@pixelpusher220]

Very informative! One thing I like to see is before and after photos to better mentally see the changes. Is there a before photo/video of the landscape somewhere?

[@shawnwillsey]

You can go to Google Earth and see it before the slide by clicking on the year in the bottom left corner. This will bring up a slide bar where you can images from different years.

[@pixelpusher220]

@@shawnwillsey "Year in bottom left" isn't there or isn't clickable. I can find dates via Street View, but none for overhead satellite imagery. And assuming there just isn't street view imagery for 1992 era

[@shawnwillsey]

@@pixelpusher220 Hmmm. My version of Google Earth Pro does show a year in bottom left (with a clock icon next to it). Make sure you are zoomed in enough to see entire slide. When I click on it, I get the timeline bar in the upper left corner. I can see the area in 1992 (in black and white, but good resolution). Hope this helps. I think its important to have Google Earth downloaded to your computer vs just using the web-based version. Good luck!

[@pixelpusher220]

@@shawnwillsey It was Pro vs web/phone feature. got it. thanks!

[@timpointing]

@@pixelpusher220 @shawnwillsey You can view the timelapse in the Web version of Google Earth. Click in "Layers" in the lower-left and turn on Timelapse. That'll show a timelapse drop-down in the top right. From that, you can adjust the speed of the playback (and pause it.) Pause the playback in 1992 and then again in 1993 and you will see the before-and-after of the slide. There is, alas, no way of simply selecting a specific year for the imagery. Also, the imagery for the timelapse is of rather poor resolution - you can see that the slide has taken place and the new course for the river, but not too much more.

[@jeffmyers7062]

Beauty !

[@maurasmith-mitsky762]

Thanks!

[@davec9244]

Thank you

[@alizabethwestra4213]

I loved your classes I MISS COMING TO COLLEGE:) Fun fact I live right where you're at!!!

[@shawnwillsey]

Awesome to hear from you. Stop by campus sometime and say hi. College classes are here if you want.

[@earljohnson2676]

Just googled earthed it wow that was huge holy crap and it pops out all I did was search for bliss ID and bam front n center amazing

[@jamiedbg51]

QUESTION!!! I live in So Cal in the Santa Monic Mountains. Where can I search for Geodes And perhaps agates? Thank you!!

[@Josh1888USU]

Dang, I wish I had seen this sooner. I stopped in Bliss a few weeks back for food and gas while traveling through. I would have popped over to see the slide but didn't know anything about it. Looking at the map seems like it would have only taken 15 - 20 minutes.

[@professorsogol5824]

A similar event occurred about 100 years ago near Jackson Hole Wyoming when a landslide blocked the Gros Ventre River. The slide damed the river and formed a lake that lasted for a couple of years and then failed abruptly, flooding the town down river. I think you would find it worth a visit. Here's a link with a photo showing the scar formed in the hill side by the removal of the slide material. en.wikipedia.org/wiki/Gros_Ventre_landslide

[@shawnwillsey]

Yes, I've been there. It's very impressive. Similar story but bigger because the clay-rich shale penetrated the mountain and was under a sandstone.

[@bobrinck1]

I looked at a Google Earth shot from 1992. Just uphill from the slide is a dark squared off area that is either water or vegetation, and in the southwest corner is what looks like a small pond. A drainage leads from this southwest corner downhill to the area of the slide. Could this have had anything to do with the slide?

[@keithfullmer1058]

Was the silt in that Glenn's Ferry formation deposited by the Lake Bonneville flood? Where did the material go that was washed away from the "scabland" area that was washed away in the Lake Bonneville flood?

[@candise9063]

Very interesting

[@Jonathan_and_Tammie]

And, you could cover another great landslide story of Bridges of the Gods and even incorporate some possible subduction zone causes.

[@annej.7125]

I remember this!

[@hebneh]

This event was only 30 years ago, yet the slide is completely undistinguishable to the eye of a layperson like me as being any different from the rest of the landscape. The vegetation looks identical and the hummocky surface seems like everything else around it. In geologic terms, the event was about a fraction of a second in the past, but you can't even see it at all if you don't know the story.

[@shawnwillsey]

It's more obvious from above or on Google Earth.

[@quintinstephens2573]

Ok, wow…the first diagram, itself, earned a like…

[@shawnwillsey]

Wow. Thanks for the kindness. Glad you enjoyed this.