Random Roadcuts #19: A Surprising Roadcut on Iceland's Route 85 Along the North Coast
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- Опубліковано 28 чер 2024
- Learn to "READ" the rocks with this innovative video series designed to help you learn geology. Join geology professor Shawn Willsey and investigate a random roadcut, make observations, and formulate basic interpretations. Here in Episode #19, we check out an interesting roadcut along the north coast of Iceland. GPS Location: 66.13021, -16.95267
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I drove through the Canadian Rockies this week. Saw lots of roadcuts and thought of you often. I really appreciate your teaching!
Thank you, Shawn, it is like reading a book with you as you walk along. The history emerges from the pages of the rocks. Brilliant.
How nice, I have often wondered about how this cliff was created. Thank you.
Another interesting roadcut. I learn something new all the time.
Another excellent roadcut!
I’m beginning to run with your analysis. You’r a great professor, very clear oratory.
Thank you so much. I learn new things from every roadcut. Thanks!!
The thickness of the lava flows is amazing. Wonder what future generations will make of the changes in the Icelandic landscape taking place in the last year or so. Thanks Shawn.
Thanks for Sharing Shawn ! I can't recall that section as I wanted to go to the Asbyrgi canyon, a place to feel humble when you know how that formed. I'll say hi when I see a guy looking at rocks when I'm in Iceland ;-)
One of the best road cuts yet. Cool descriptions.
Thanks, Shawn--we especially enjoy you helping us read the roadcut's stories-
Thanks for the video, one always can learn a lot just from observation,
Cool road cut! Interesting layers. 🙌
What a view, gorgeous 🤗
I thoroughly enjoy random roadcuts… always an interesting set of rocks. Thank you
Thank you Shawn
I’ve been paying close attention to the Rapidan Dam disaster in Minnesota and you can get a very good view of the newly exposed cliff face from a number of drone videos
Thanks! Love your road cuts series. So much to explore and learn.
Thank you Shawn another great video
So enjoyable. Thanks 😊
I did wonder of some of this sediment was going to suggest a lahar but I guess because those are long and narrow and related to specific short duration events, genuine lahar sediments are actually quite rare?
I don't think Lahars are rare per say its just the wrong kind of climate as you need a higher ratio of rock/ash compared to water else you just get a Jökulhlaup instead. Lahars usually involve a lot of volcanic ash rather than effusive lava with water coming more often than not from rain or small glaciers/ice caps or crater lakes. Then there is the mix of stuff erupted by the volcanoes of Iceland where while more siliceous magmas do erupt on occasion the eruptions for most of these volcanoes tend to erupt a larger effusive component which helps hold ash layers in place. Notably lahars generally come from towering stratovolcanoes but all of Iceland's towering stratovolcanoes have active ice caps not just mere glaciers around their summits this means again you have too much water to end up with a lahar. Perhaps in principal one could happen if you had a pulsed eruption with a brief intermission too short for large amounts of ice to accumulate after the first eruption destroyed the ice cap but that is unlikely.
I’m hoping to visit the Northern part of Iceland next visit. Gosh, that road cut has definitive layers.
I loved how this began "the nice thing about Iceland is there tends to be little if any traffic" you get started and it's like being in Utah again lol traffic everywhere. Cracked me Up!
Cool, thank you.
Cool. Followed right along with your observations and reasoning.
Thanks!
Interesting, as always! Thank you so much! I bet you haven't found any road cuts in Europe yet, but there will be increasingly the further you get upstream😊
Great vid! Ty
Hey, Shawn. I really enjoy these roadcuts. I remember you were down in SoCal awhile back and did some roadcuts and other things about the San Andres Fault. I was wondering if you have ever thought of doing one of your roadcuts on where the San Andres Fault crosses Highway 14 just north of Los Angeles? I've managed to stop there once and take some pictures but I would love to hear a geologist's thoughts on it. Since it is a major artery to LA I recommend going on a Sunday morning, otherwise the traffic will drown you out. The sun will also be shining just right onto the West side of the cut. Also, up Angeles Forest Highway and Angeles Crest Highway are more roadcuts you might find interesting. But, by far, where the San Andres crosses the 14 is just amazing!
Thx Prof ✌🏻
Thanks for introducing us to a roadcut and the geology along Route 85 on the north coast. Wondering? Might any of the fine-grained sediment be an ash deposit?
I love random road cuts
Everyone I ride with drive so fast we never get to stop
Tho I do ask ❤
Round deposits, covered by a mud deposit. 1) Possibly an ancient river/wash/delta that becomes a lake or bay. 2) Possible wash/river that got covered by an alluvial fan.
Or maybe glacial till? That might explain the poorly sorted deposits.
So from bottom to top glacial till with the glacier turning to flowing water possibly back to glacier then stream again before lava came through several times with weathering in-between.
Wondering if that layer with angular rocks represents a glacial lagoon like environment where ice floes transported rocks above a body of water and, as they melted, they dropped them as erratics onto the bottom?
Are they truly random or just conveniently located? 😂 Really appreciate what you are doing with your channel.
Thank you, Shawn, for another pretty cool random roadcut, and an Icelandic one at that! :) This is only a few kilometers from Ásbyrgi if I'm not mistaken, have you been there?
Yes. It was very cool.
Hello, would a volcanic lahore leave the same of mixed rock and fine dirt? Jillian
A glacial moraine on a bed of water followed by multiple lava flows?
Lava flow on top of glacial outburst flood deposits?
Shawn your a Rock Star, not a dirtologist like others :)
Was this from your latest trip?
Another Iceland Supervolcano roadcut.
Take a drink every time basalt is spotted.
There is no known Icelandic "super volcano" I think the largest known explosive eruptions from any known Icelandic volcano on the VEI index tops out with maybe a 7 but more likely and well established eruptions top out as VEI 6 eruptions. Maybe one existed millions of years ago but if so it hasn't left a trace.
@@Dragrath1So, you don't know what a supervolcano is.
I'll explain. The whole of Iceland is a mid-oceanic plate mantel-plume hotspot, like the Hawaii hotspot, and like the (now) Yellowstone hotspot _was_ before it was covered by the North American plate some 50mya.
Mid-oceanic supervolcanoes erupt differently than continental supervolcanoes because the oceanic plate is far thinner so the pressure does not build up into massive continent-covering andesite ash explosions and lahars. However, they do pump out a lot of runny basalt.
The only real difference is that the Iceland hotspot is currently parked under the mid-Atlantic rift zone where the lava it produces can follow the path of least resistance to the surface along the rift, so it erupts every couple of years, rather than every couple of dozen years like Hawaii, or every 640,000 years like Yellowstone.
@@Theranthrope Um no that is not the definition of a supervolcano, that is a mantle plume driven hot spot.
The current definition in literature refers to the subset of large caldera complexes capable of producing explosive volcanic eruptions which exceed 1000 cubic kilometers of erupted material. If this condition is not met then it is not a super volcano.
To Quate straight from the USGS: "An eruption is classified as a VEI 8 if the measured volume of deposits is greater than 1,000 cubic kilometers (240 cubic miles). Therefore a supervolcano is a volcano that at one point in time erupted more than 1,000 cubic kilometers of deposits."
Does this definition have problems? Why yes it does especially given that undertianty estimates of ancient ash deposits vary wildly or that it fails to account for the potential to produce large voluminous super eruptions in the future.
Personally the large upwelling plumes responsible for Large Igneous Provinces and associated lingering hot spot chains would be a more deserving target for being called super volcanoes but I did not coin the definition the interaction between scientific literature and media reporting did. It also should be noted that the only recognized "supervolcano" which is directly plume driven/fed is Yellowstone all other geologically young "supervolcanoes" occur within active continental rift systems or subduction back arc basins with the other sole exception of the Gakkel Ridge caldera the active mid ocean ridge of the Arctic ocean a very slow spreading mid ocean ridge system which appears to spread so slowly that magma is able to pile up and cool undergoing large scale crystal fractionalization into more siliceous melts.
Gakkel ridge thus unlike other known mid ocean ridges erupts more viscous silicious material which can erupt far more explosively even at great depths with evidence for large ignimbrite deposits in the geological past from Artic core samples at least one from 1.1 million years ago which is large enough in volume to meet the definition for a supereruption and much more recent smaller vulcanian eruptions from the ridges associated chain of deep ocean stratovolcanoes.
@@Dragrath1 You, yourself, don't seem to understand the information you posted. A supervolcano is not defined by it's VEI potential or caldera size.
The Yellowstone hotspot over the last 50 million years has been a Hawaii-like island chain arc, a massive flood-basalt igneous province which buried the Pacific Northwest in two miles of lava, and a series of massive andesite explosion calderas.
It was a supervolcano in each eruptive phase. The difference in phases was due to the thickness of either the oceanic or continental crust that it was erupting through.
There are other types of supervolcanoes, which are one-offs where a subducting plate pinches-off into the lower mantel and creates thermal instability in the upper mantel which expresses itself as an supervolcano arc. This happened in the Miocene when the Farallon plate pinched-off and created an arc of supervolcanoes in Colorado and New Mexico. Peach Springs in Arizona was created a similar way.
Yet another type is the mid-continent rift supervocano, like the active AFIR in West Africa, where a hotspot is parked in a rift zone like with Iceland. The Mid-Atlantic NAIP rift started this way in the Jurassic.
You just see supervolcanoes as the andesite explosion type when there's a lot of other types out there.
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There are no road cuts in my area it is all flat coastal plain sitting on 20,000 feet of mud. I have to go to the hill country to get to see road cuts.
Why can’t i access the new lava lake video? It comes up “private/unavailable.” Cry Cry
I need to fix it and relaunch. Apparently it was glitchy.
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