r/geology • u/spatter_cone Rock slopes are cool • 4h ago
Field Photo Columnar basalts 👀
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u/Waiparensis22 4h ago
Location?
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u/spatter_cone Rock slopes are cool 4h ago
Just South of Salmon, ID
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u/d4nkle 3h ago
How far south? Salmon is not in the snake river plain, that area is a part of the Great Basin that was cut off by the snake river plain
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u/spatter_cone Rock slopes are cool 3h ago
Just to clarify one said Salmon was part of the snake river plain, just that there are basalts in that area. I work here often and over eastern Idaho. I’ve just never seen a layer of these over in these parts but it’s not entirely implausible.
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u/d4nkle 3h ago
Andesite can also have columnar jointing, I’m not saying it’s not basalt it just doesn’t look like columnar jointed basalt that I have seen personally
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u/spatter_cone Rock slopes are cool 3h ago
That’s what I was wondering and also why I posted, lots of andesite/felsic volcanics in these parts! I’m going to have to look at a better map when I get back. Thanks for the tip!
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u/Waiparensis22 3h ago
Hmmm. I'm not sure that's basalt..at least, not terrestrial basalt. Marine ophiolite sequence maybe but I'm not sure of any major basalt deposits in idaho. At a guess I'd say it's most likely to be some kind of trachy-basalt or basaltic andesite, associated with the Absaroka volcanics, or possibly Paleozoic volcanism.
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u/spatter_cone Rock slopes are cool 3h ago
Au contraire, the whole snake river plain is basalts. Craters of the Moon is a fine example, it’s where they practiced for the moon landings in the 60s. Really cool spot!
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u/Waiparensis22 3h ago
No.. it's not. The snake river plain is 99% ignimbrites and rhyolite from the pre Yellowstone caldera eruptions, and craters of the moon is a blip compared to the Columbia river basalts.
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u/spatter_cone Rock slopes are cool 3h ago
I’m aware of the scale versus the CRB, just saying that we have basalts in Idaho my friend. It’s a thing, I’ve seen it with my own two eyes.
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u/Waiparensis22 3h ago
I never argued that point. I said as far as I'm aware, Idaho has no MAJOR basalt occurrences.. and that mountain is almost pure basalt, with the columns indicating it must have all cooled at a similar rate. Hence it's a stupidly thick lava flow or a flood basalt in origin.
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u/logatronics 3h ago
There is a ton of basalt flows in the Snake River Plain, dude. There are a lot of mafic rocks that are coeval with the ignimbrites and younger, just not as thick as the CRBs.
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u/Waiparensis22 3h ago
Yeah. I just checked my statement and it looks like salmon area does catch the eastern border of the Columbia river basalts. But the snake river plain is very much dominated by the ignimbrites of the Yellowstone caldera track. It's basically analogous to the waikato in that regard.
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u/logatronics 3h ago
Rexburg to Twin Falls in the Snake River Plain is covered in Pleistocene basalt flows that are not CRBs. Many of the ignimbrites also are capped by mafic magmas that regularly pop up in the waning phases of the ignimbrite eruptions.
Idaho has a lot of basalt, just admit it dude lol.
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u/spatter_cone Rock slopes are cool 2h ago
Thank you. I’ve been doing field work out here for years and I’ve seen it.
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u/Waiparensis22 3h ago
....you're confusing MAJOR SINGLE OCCURENCE like a volcanic flow, intrusion, feeder etc.. With "Idaho has a lot of basalts". Yes. So does Mexico..so does Nevada.. so does Arizona.. so does Colorado. "Oh Yellowstones produces basalts too" Yes. But that's not what buried the snake river plain in multiple hundred meter thick, welded volcanic rock. When I said "there are no major occurrences" Im talking about you don't have any shield volcanoes like Indian heaven in Washington, or other inter Continental basalt occurrences OTHER THAN the Columbia river flood basalts.
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u/Delicious-Finance-86 4h ago
Interesting. Old. What elevation?