Yellowstone's Most Explosive Eruption: See the Evidence Up Close With a Geologist

[Music] all right friends I worked extra hard for this one so I hope you enjoy this um I am east of Mammoth Hot Springs and maybe about 2,000 ft above the valley floor this is the Garder River uh flowing to the north to the town of Garder out the north entrance of the park of course this was the area uh they had the floods in June of 2022 I actually had to take off my shoes and uh Ford across the river cuz the foot bridge is uh washed out um and it was a much bigger hike than I anticipated um but but I really wanted to come up here um I'm not looking forward to going down but let's focus on what's up here um I'd actually seen this location in photos you can see it from a distance you can see it from Mammoth with binoculars you can see some of the features um and I've read the writeup on this and I just knew I had to get up here one way or another unfortunately there's no Trail so it was a a pretty steep and and pretty tricky climb up here but what we've come to is we're just just off the peak of a mountain called Mount Evers not Everest that's in the Himalayas Everts EV TS um and most of this mountain at least off here to the um to the north is made out of these kind of drab cream and Gray colored um sedimentary rocks these are Cretaceous these are about 70 million years old uh these were deposited when there was a big Inland sea in the western us so these would have been Shoreline deposits streams flood planes that were dumping into that uh river system and um those actually project over into here where my backpack is except you'll notice that they're a different color they're a little more reddish and the real star of the whole show is uh this contact right here let me see if I can back up a little bit so you can see a little bit more of it here and so what we have above us here this is the Huckleberry Ridge tough this is the 2.1 milliony old first of the three big Yellowstone eruptions um kind of inundating this landscape here and this contact zone is just really instructive and just really spectacular so let me see if I can walk you through it here um so the reason we have the color change in these Cretaceous sedimentary rocks is that the heat the actual heat of of this ash as it poured across this landscape baked into the subsurface or into the the rocks that were at the surface these Cretaceous rocks and actually oxidize them to some degree you can see a nice brick red paleosol here and then the uh the sandstones right here kind of forming this kind of pinkish color as well um and so we've got the Cretaceous rocks here mining their own business for a good 70 65 or so million years then this colossal eruption this big massive eruption of the Yellowstone region uh first forms a deposit of what we call um uh ashall tough so this tough here you'll notice is super soft and crumbly uh just powdery but super crumbly so this would be the initial eruption uh sending Ash up into the atmosphere and then raining down and blanketing the landscape so that's what this good um it's probably maybe 2 m or so from down here up to where it gets a little darker that's what all this represents and you can see it was sort of fine in the initial stages this really powdery material but as we work our way up into here uh gets a little more granular um so now we've got little bit larger particles probably tiny pieces of pmus falling out of the sky and then just when you thought the worst was over with the ash falling out of the sky a good 6 ft or 2 m of Ash then we have this massive and I'll I'll walk around the corner a bit so you can get the full scale of it then we have these pyroclastic flows these big hot Avalanches of Ash coming barreling across the landscape and they're so hot that they fuse some of this ash here so you can see it goes from being kind of granular I can rub it with my finger to being completely literally rock hard right in here and this pyroclastic flow as it's moving across the landscape the bottom even though it's very hot it's uh coming in contact with the ground so that part of the pyr classic flow is cooling quite quickly forming this darker uh very glassy tough so we can see some of the crystals in here these little white and shiny pieces uh but the black stuff is is much like obsidian in a way it's very glassy in nature um and as we move back a bit from the cliff on this heinously steep slope um let's look this way with the sunlight we can see that it gets a lot more light colored up above but this is all part of the Huckleberry Ridge tough and this is just sort of a classic um depiction of how these things progress from the red uh paleosols the red baking of the subsurface materials here the initial uh ashall tough the white tough that we see here that blanketed the landscape and then this would be what we call an ash flow Tuff this was the pyroclastic flow moving across the landscape and it had so much heat and so much um I supposed density in terms of just crystals in it that it just fused uh together to form this resistant unit that caps the top of this mountain um really pretty remarkable um let's see anything else in here that's pretty neat well one thing that's kind of cool here is you can actually also see um the orientation of the bedding here so these Sandstone layers and you might be able to get a sense over there as well are dipping uh to the North or to the to the Northwest I suppose uh in that direction and we can see that to some degree right here these beds are dipping in that direction down away from you and look at the relationship then between those beds here's the Sandstone Cretaceous sandstone and there's the ash right there so we have a really pronounced angular unconformity and unconformity is a contact right here where my hand is that represents a large period of geologic time between two units we've got 70ish milliony old Cretaceous Marine Sandstone sitting under sitting underneath this 2.1 million year old volcanic deposit and right along the contact you can actually see some of these chunks have been ripped up so these are called rip up classs um just sort of an erosional surface that the ash then blanketed uh as it as it moved across this area or as it was deposit on this in this area and then the py clastic flows kind of came over the top of it um um see if we see anything different down here looks like there's quite a few clastic dkes kind of cutting through it as well um but really just remarkable and um it was a sucky hike uh the last hour or so it probably wasn't worth it then but now that I'm up here and caught my breath and my shirt is sort of drying out um it's definitely worth it so uh this is the Everett formation Cretaceous age material IAL and then part of our pyroclastic flow and Ash Fall tough from the eruption of the uh first Yellowstone uh Caldera what's sometimes called the Island Park created the Island Park Caldera and deposited this thick sequence of the Huckleberry Ridge tough 2.1 million years ago just a little further down the hill you can get a sense I think the cliffs get a little taller down around the way um here they're probably getting close to 80 to 100 ft but I think they get a little thicker as you go that way but great view Mammoth Hot Springs the Gallatin range in the distance um shoot I'm too far close to the cliffs around the corner you can actually see Yellowstone Falls got the Garder River down here uh and then looking North into Montana so hope you enjoyed this one a lot of effort went into it so enjoy

Channel: Shawn Willsey

Views: 41,562

Keywords: shawn willsey, yellowstone, yellowstone eruption, huckleberry ridge tuff, mt everts, mammoth hot springs, yellowstone supervolcano, yellowstone caldera, island park caldera

Id: MJHZ72GVgFg

Length: 9min 28sec (568 seconds)

Published: Tue Dec 12 2023