The Geologic Story Behind Upper Mesa Falls on the Henrys Fork River in Eastern Idaho

Geology professor Shawn Willsey takes you to Upper Mesa Falls to understand the geology behind the scenery and landscape of this beautiful location in eastern Idaho. Located just west of Yellowstone National Park, learn how huge eruptions of ash and fluid eruptions of lava have shaped the Henrys Fork River and the falls.
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Shawn Willsey
College of Southern Idaho
315 Falls Avenue
Twin Falls, ID 83303

[@mmiller73]

Very insightful! I have visited the Henrys Fork many times as a fly-fisherman and have stopped to see Upper Mesa Falls on a couple of occasions. It’s really magnificent! The geological and natural history of that area has interested me for decades. I recently watched a lecture by Dr. Dennis Shiozawa about the evolution of cutthroat trout and he gets into a lot of the geological history of the Snake River and surrounding area to explain how cutthroat trout got into different drainages and even crossed the continental divide. One of the claims that he makes which really fascinates me is that the ancestral Snake River was once a tributary of the Sacramento River via the Humboldt and Pit rivers until about 3 million years ago when Lake Idaho over spilled its northern basin into what is now Hells Canyon and captured the Snake River into the Columbia in the process. I would love to hear more about this claim!

[@WayneTheSeine]

Same here. Until recently, my wife and I would make a yearly, month long, trout fishing pilgrimage, from Louisiana, out west...starting in Montana, then south into Idaho, Colorado and New Mexico. I have such great memories of the Henry's Fork. BTW, I also had a great solo trip on the Flathead...some fine cutthroat there.

[@byronleatham1183]

Upper and lower Mesa falls are totally awesome, and some of the best waterfalls I've ever seen.

[@shawnwillsey]

Totally agree!

[@booshday]

I agree they're awesome and I love Shoshone falls as well.

[@chandlerkholkni]

Pretty freakin happy that just a month or two after I asked if you could do the Island Park area you’re here doin it! Make sure you stop at trout hunter for some food, can’t beat it up here! Also if you could stop into the centennial valley on the north side of the centennials on the Montana side and explain how it was formed thatd be MUCH appreciated. That valley has fascinated me since I moved up here!

[@glennquagmire1747]

Fascinating 👍

[@marklang5169]

Thank-you again Shawn. Your diagrams are a great help in understanding the concepts.

[@patrickkillilea5225]

Wow! That's a beautiful place. With flowing water... We don;t have much of that down here! The video was great, and very interesting,

[@shawnwillsey]

Glad you enjoyed it

[@lisaloy2011]

Loved this video. Sent it to my 83yr old dad across town and he loved it. He's seen many of your videos. Next time I'm at their house, I have to subscribe him to your site.

[@shawnwillsey]

Awesome comment and I love that he enjoyed it. Please help him subscribe.

[@rogercotman1314]

Thanks Shawn. Another amazing and educational volcanic video. 322 like

[@earlreaganjr9381]

Nice video. We visited Upper Mesa Falls in 2021 & thought they were great. Thanks for the geologic history. We had no idea. The tuff rock formations with the falls mist is really cool. It seems to create a mini rain forest!

[@J0hnC0ltrane]

Amazing! 400 feet thick ash. That was quite a volcanic event. The layer of ash also has vertical fault lines like the basalt layer. Thanks.

[@jackprier7727]

Okay, you showing the river following the contact-zone of the basalt flow against the older tuff and why was delightful-

[@Rachel.4644]

Whoa, dramatic and gorgeous falls..... and tuff....! Enjoyed very much. ❤

[@Fryed_Bryce]

Gosh dang it Idaho is so cool. Hilarious how much i completely took it all for granted growing up here

[@WayneTheSeine]

So glad to have seen this pop up on my recommended list. Mesa Falls is a beautiful spot. It is nice to now know how it came about. I was there one year when five French hikers had to deal with a grizzly charge while hiking somewhere near that area. After emptying five cans of bear spray, their last one, the bear finally gave up the charge. So, it seems grizzly's have made it to Island Park.

[@rockweiler777]

A great illustration of this falls' split personality! Thank you for another fantastic share!

[@3xHermes]

Great location and video, thx!

[@jokerace8227]

I would love to know more about the geology just to the North in Madison Valley, down to Ennis Lake, Montana if you haven't already.

[@joedoe6444]

i like this whole area around island park. from the Messa falls to all the springs further north, and quake lake in Montana. also, there is a little-known road just south of these falls that goes into Yellowstone Park to the cave falls area. if you look on a map it is a huge number of falls all in a relatively short area. the best part about cave falls is their is almost never anyone around there. i have been to Messa falls many times before, but learned more about them in this clip than from the signage around the area or in the visitor center.

[@winnieg100]

Very interesting and informative.

[@valoriel4464]

Thx for another grt geo-adventure ✌🏻

[@pmm1044]

Like multiple Tieton andesite flow deposits in Tieton River valley on east slopes of cascades

[@davidk7324]

Thank you Shawn. Truly a hidden gem off the beaten path. The Big Falls Inn (Mesa Falls Visitor Center) is run by the Caribou-Targhee NF and Harriman State Park and contains several education tables of locally sourced and labeled minerals/rocks. A power company built the Big Falls Inn for their use in ~1915. The walkways and platforms are very well done and it's about a mile hike to the Lower Falls overlook. Bears are abundant and spray may be required for the trail to the lower falls. The site has been open widely to the public only since 1986. Are the Huckleberries in Eastern Idaho looking promising this year?

[@BakerBaker-xc3uh]

Amazing inspiring geological information! Thanks so much

[@qrplife]

geologic time scales blow my mind.

[@sunnybnny]

Thanks!

[@shawnwillsey]

Thank you for your donation.

[@Anne5440_]

A really beautiful hidden gem. At the start of the video I thought the lower river would be following a fault line. Now I realize it is following the contact edge of the differing harnesses of rock. Thanks for a good lesson. I'm watching cams from iceland to see if the volcano you sampled lava from will erupt again this weekend.

[@skyedog24]

Whether you intended to or not you explained it to me perfectly as though I were five and thank you.very interesting.

[@brendanacord]

Tourists: Ohhhhhhh, waterfall! Shawn: Ohhhhhhh basalt!

[@douglasdunn7267]

Thanks! Come back to Montana again!!

[@shawnwillsey]

Thanks for your kind donation. Let me know some areas of interest and I will try to plan a trip.

[@kathat4235]

Fascinating! I'm new here. Been watching your vids on Iceland. I'm in California and my favorite beach is @ San Gregorio, near Half Moon Bay. I've always wondered about the cliff formations there. There are 3 different types of rock. Would be interested to learn the story of what happened there. I'm inspired to seek and find... :-)

[@davidleadford6511]

As a kid, they didn't have that fancy viewing platform to view the falls. All they had were dirt trails. I use to walk right out to the edge of the falls and sit down on a rock and watch the water fall into the river below. Still amazes me with all the things I did as a kid I survived. As recent as 29,000 years ago. Seems people's claim that the Yellowstone Volcano hasn't erupted in over 700,000 years is a tad bit inaccurate.

[@kimbsun1]

I also remember climbing out onto the edge of the rocks and sitting on the edge of the walls near Mesa Falls, when I was about 10 years old. As a parent, I am grateful for the improvements because I'm sure my 11 year old would do the same if not for boardwalks & rails.

[@davidleadford6511]

@@kimbsun1 Me too.

[@neallandsberg2678]

Thanks

[@shawnwillsey]

Thank you!

[@charonsiouxsie949]

State tourism department should link your channel. I want to visit Idaho again, bad.

[@shawnwillsey]

That would be cool!

[@geomodelrailroader]

Mesa Falls 1.3 million years of lava rock and water formed it. It is amazing just one volcano in Yellowstone formed this canyon, the Henry River, and Island Park.

[@cbhirsch]

What is causing the fall line? Why is the tuft there more resistant than the adjacent rock?

[@darrenmarney8577]

Great Question 👍 👌

[@davidk7324]

I think subsequent lava flows (over the pyroclastic tuff depositions) form the edge of the falls. Basalt holds up better over time but still erodes off chunks. Hopefully Shawn will be along to let us know if this is correct.

[@shawnwillsey]

The lava diverted the river to west where it eroded the tuff. Not sure why falls are in that exact place

[@laurienielsen8031]

Shawn, I am curious about where the western side of the Rockies are. Are the Hints and the Wasatch part of them?

[@shawnwillsey]

No. Not geologically although the Uintas are uplifted around the same time as the Rockies. Look for some Uinta Mtn content early fall.

[@timothkeyyprice]

I may have missed it. What forms the edge of the falls?

[@charliewatts6895]

Shawn those falls look like the ones in Iceland that you visited - at the bottom of the falls the river makes a right angle turn. Not sure if the resemblance means that they are of the same geology?

[@lauram9478]

❤

[@hyrumhanson3390]

Lot of bears winter in the fissures in the basalt flows

[@jennlheck9349]

I live three miles from the falls there are the upper and the lower they falls are so dangerous the navy seals stopped training there after they lost a few to drowning

[@kenbrady119]

I love your local geology! I'm not so big on your long-distance ventures. I'm a biologist, and have given up as much as possible on burning hydrocarbons like jet fuel and gasoline because of the damage the CO2 does to so many living creatures. Live/work locally and sustainably. But thank you again for your love of Earth and its history.

[@laurieedeburn2449]

share

[@John-ir2zf]

I always get an awkward feeling when im standing among normies at a geologic wonder.... and they have no idea the story behind what they are looking at !

[@shawnwillsey]

I'm used to it at this point.

[@darrenmarney8577]

So once again Shawn ! I'm finding myself focusing on potential rock climbing ! It's guaranteed that I'm going to be your student of least potential 👌 Awesome visualisation of the area 👍

[@stevewhalen6973]

Thanks!

[@ReclinedPhysicist]

Thanks!

[@shawnwillsey]

Thanks for your generosity. Much appreciated.

[@farmermark2067]

Another great educational video Shawn! Thank you. One question... What was the source of the 29,000 year old basalt flow? I'm assuming it must have something to do with the Yellowstone hotspot? Keep the videos coming please!

[@shawnwillsey]

A local shield volcano within the caldera.

[@farmermark2067]

@@shawnwillsey Thanks Shawn!

[@nitro13333]

The erosion of the falls upriver should be quite aggressive since the tuff ash - despite being much more compact, as you noted - is much less resistant than the basalt neighbour on the margin?

[@neallandsberg2678]

Thanks

[@shawnwillsey]

Thank you for your generosity!

[@jefferyherdrich3043]

Very good explanation!! If you travel back toward Ashton on Hwy 47 to the Bear Gultch info sign, behind you is a gravel pit with a sandbar on top, only sand in the area. Would be curious to hear your interpretation. Keep up the good work.

[@shawnwillsey]

Cool, thanks!