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Posted by Ballpark Frank (69.178.8.75) on 12:00:01 03/19/17
In Reply to: Raspberries!!! posted by Beej
Beej,
With all these years of both walking and skiing under Overhanging Cliff when the road is closed, I have not noticed the contact swirls you speak of. I'm not sure I would know what I was looking at if I had seen it. When Paul Doss was the park geologist in the wake of Rick Hutchinson's tragic demise, he pointed out the obvious contact zone that you can see up high on Mt. Everts from Mammoth, and told me he really wanted to get up there sometime to check it out. I know there is a thin horizontal layer of white and a thin layer of red above or below the white layer. Unfortunately, Paul didn't hang around very long before he couldn't abide the federal bureaucracy, and returned to academia, so we never got around to that. If any of those contact swirls are visible at Overhanging Cliffs or Sheepeater Cliffs, I would love to have you point them out once I am back "in town".
I just read some USGS info on how they think the source vent for possibly both the Junction Butte flow and the Huckleberry Ridge tuff on Mt. Everts was just northwest of Blacktail Ponds, and there is evidence of scoria and cinders in outcrops. I need to check that out. I know I have seen cinder cones at Craters of the Moon, Hawaii Volcanoes, and possibly, Lassen Voclano (can't recall with certainty). It would be nice to see evidence of one so close to the road in northern Yellowstone. I'm including a link to the USGS paper, in case you are curious.
Paul Doss was big on the biogeology concept, and pitched an overview at seasonal interpretive training back in May or June of 2001. It really changed my perspective on places I visit in Yellowstone, like Hayden Valley and the Central Plateau, which both are classic examples of geology playing a significant role in determining the vegetation.
One last thing: You mentioned how the rock was too old to radio-carbon date. In the linked paper, there is mention of "stable reverse remnant magnetic polarities", typical of the flows at the Grand Canyon (of the Yellowstone) and Tower Creek, and contrasting it with the two flows on Mt. Everts, which are normally polarized. I'm curious as to whether they have tools that enable them to gauge polarity in the field, or if they have to take a specimen into a lab environment for assessment.
Sounds like we need a geology "field trip" on the Northern Range, and if it coincides with berry season, all the better. (I need to check on the pikas at Sheepeater Cliffs.)
Ballpark
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