Thanks one more time. Just brought my archeologist friend in CA (Monterey) on board as a subscriber. She has begun her binge watching to work at getting caught up on all your presentations!
Thank you for this, Professor Zentner. Rocky Crandell was my great uncle (his older brother was my grandfather) and I had always heard that he was famous for Mt. St. Helens but never the details of why. Now I know. Fascinating!!! Also, it's good to see someone still using chalk on a chalkboard. ;-)
This video was incredible but I love all your videos, so thank you. Now, the interesting thought that occurred to me while watching this video: I live in Grand Forks BC Canada, just east of Kelowna, about just under two hour drive right on the Washington state border, the geology here is just incredible but that's for another time. What interested me is the direction of flow of all these mudflows because I started thinking about native legends of the area. I've heard, and I can't verify this to be true but all my life I've heard that the natives wouldn't settle in our valley, something about spirits and death and a bad place to live, most importantly that they don't live in valleys running east west, bad spirits, etc, although I've never heard from a native the exact story, nonetheless I've found it a little disconcerting as I don't dismiss native legend. When you consider the native legends of Orca and Thunderbird and how those stories are related to large earthquakes on the west coast, it's very plausible that the natives where telling important stories for people's safety. So, I started thinking about all these mudflows and it seems to me they all run east to west and I finally found a plausible explanation for the legend or stories of why natives wouldn't settle our east west running valley. I know, it's pretty loose but still I imagine if anyone had witnessed the aftermath of Osceola, a legend would have to be born and if they had legends over hundreds of years all in east west running valleys it actually makes perfect sense. At any rate, I don't know if you'll see this Nick but I thought you might like what I've come up with, at least in novelty although I would never discount native legends. Those stories had a reason for their creation and for the telling to keep people safe.
I wish my mom would have seen this presentation of mt. Rainier. in 1980 we lived at the crossection of I 5 and and the 512 access road. There is a huge mcDonalds there now. but once we were in apts that had a magnificent view of the mountain. Our only vacations were driving up to mt Rainier, camping or day hikes. the area has changed so much since then.
I remember when Mt. St. Helens blew in 1980. It was very overcast here in San Rafael, CA for a while. Then I had a student who got stranded in Paris when a volcano in Iceland erupted a few years ago. The airlines had to cancel flights out of Europe til it cleared enough to be flying safely. Imagine: Stranded.. in Paris... in springtime...sigh..
The Osceola Mudflow of 5,600 years ago was Mount Rainier's signature event during the Holocene. During a period of eruptions, avalanches caused 2 to 3 km3 (0.5 to 0.7 mi3) of mainly hydrothermally altered material from the volcano's summit and northeast slope to slide away. This lahar swept down the west and main forks of the White River, passing the location of current day Enumclaw before reaching the Puget Sound near present-day Auburn. The Osceola collapse left a 1.8 km-wide (1 mi-wide) horseshoe-shaped crater, open to the northeast, almost the same size as the crater produced by the 1980 eruption of Mount St. Helens. Most of the Osceola crater has been filled in by subsequent lava eruptions, most recently about 2,200 years ago. Osceola deposits cover an area of about 550 km2(212 mi2) in the Puget Sound lowland, extending at least as far as the Seattle suburb of Kent, and to Commencement Bay, now the site of the Port of Tacoma. The communities of Orting, Buckley, Sumner, Puyallup, Enumclaw, and Auburn are also wholly or partly located on top of deposits of the Osceola Mudflow and, in some cases, of more recent lahars as well.
Wonderful to see this in the UK again, this is my favourite of all your lectures. Really superb and fantastic slides. Thank you so much for the re-upload after the copyright issue blocked it here. Judging by many of the comments posted, you have a surprisingly big UK fan base. Have you thought about doing a patreon thing as I should be delighted to support you?
Dr. Zetner, I wanted to ask if you can/could explain what caused the earthquake here in MD (epicenter was in VA) in 2011? I read somewhere that it was due to the east coasts mantle slipping, but you would know better than me.
so technically speakin', does a lahar give rise to a melange? or is the geologic result called some thing else? 40:00 that looks like a chaotic deposit if I ever saw one, yah...
Asking here because it’s the most recent post, lemans question could the effects of climate change, melting ice/more fluid water, and increased surface temperature cause an increase in geological movements due to the extra pressure of the water on the ocean plates and warmer continental plates being “ softer”?
Geo Major throwin ya a bone, neither of these sound theoretical mechanisms are going to affect tectonic activity in any significant way. A rock that is even 10 degrees warmer than before is not appreciably softer or weaker. Melted terrestrial ice making water deeper and oceans heavier is also a drop in the ocean (if you'll excuse the turn of phrase) next to the already typically lively environments along many coasts, and the daily effect of tides. It's the effect of its loss on land which is more significant though, since ice and crust together raft atop the semi-liquid mantle, if you lose that ice quickly from the top, then like throwing something off a boat the land there will locally experience a force to buoyantly rise, since it's still got its 'hull' of 'light' crustal rocks beneath it. This is observed occurring still long after ice sheets have retreated, and is termed Eutectic Rebound.
@nickzentner a couple of quick questions : granite comes from solidified magma you said. And Mt Rainer's lava stayed inside the park. Yet you said Tacoma is sitting on granite. AND the "mud flow" followed the river - yet again, that's way outside of the park. Last one, I promise, when I hear "mudflow" I think water + dirt = mud. Yet again, at the river you pointed out the boulders frozen in place by the lava - again outside of the park. Sorry professor. I pay attention to my teachers !
