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Brushbuffalo
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Joined: 17 Sep 2015
Posts: 1887 | TRs | Pics
Location: there earlier, here now, somewhere later... Bellingham in between |
| Anne Elk wrote: | | So there you have it: anastamosizing frost-heave pseudo-pingo feedback loops! (Maybe I should stick to brontosaurus theories). |
Anne Elk, I love your theory that you have. And it's yours. (apologies to Monty Python).
I too ruled out pingos due to lack of any probable recent permafrost. However there are relict periglacial features in many areas lacking any recent permafrost, such as 'stone stripes' on hills southeast of Yakima and elsewhere. But the story gets more intriguing because even stone stripes, formerly believed to need permafrost to form, now are thought only to require freeze-thaw cycles without permafrost.
The point is that as more observations and analysis occur researchers are able to better understand what is seen in the world. As time goes on and more research is done, earlier ideas are often revised or even rejected if they don't fit the evidence.
Such is the nature of good science.
Passing rocks and trees like they were standing still
Passing rocks and trees like they were standing still
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Brushbuffalo
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Joined: 17 Sep 2015
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Location: there earlier, here now, somewhere later... Bellingham in between |
| puzzlr wrote: | | Sometimes I know, but mostly just wonder. |
Monty, this applies to us professionals too! The difference is that we know enough to come up with multiple working hypotheses instead of just wondering.
Sometimes one of our hypotheses might be correct.
At other times ( often, if we're honest) we just wonder too!
And finally, Monty, you can contribute( and have, you Middle Fork expert, you!). You go to many places and see much cool stuff. Send it on ( with picture, scale, and location), for us to marvel at and hypothesize about.
Passing rocks and trees like they were standing still
Passing rocks and trees like they were standing still
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texasbb
Misplaced Texan
Joined: 30 Mar 2009
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Location: Tri-Cities, WA |
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texasbb
Misplaced Texan
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 Sun Dec 20, 2020 4:29 pm |
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| Brushbuffalo wrote: | | puzzlr wrote: | | Sometimes I know, but mostly just wonder. |
Monty, this applies to us professionals too! The difference is that we know enough to come up with multiple working hypotheses instead of just wondering. |
Which means you experts wonder more than us ignoramuses. I feel better about myself. 
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Anne Elk
BrontosaurusTheorist
Joined: 07 Sep 2018
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Location: Seattle |
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Anne Elk
BrontosaurusTheorist
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Tue Jan 19, 2021 12:36 am |
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Some folks who watch this thread might have missed the one that Kim Brown started in PNW History a while ago about Prof Nick Zentner's entertaining geology presentations. I just discovered that he's recorded the first two weeks of this year's CWU Geology 101 class, although there's no direct link to the lectures from his website in the Geol 101 tab.
Any of the rock hounds frequenting this thread who are interested in geology "basics" can access them by searching in Youtube for "Geol 101 Zentner". I just watched "Rocks of North America" As per his usual, the first 10 minutes of each video are social patter and you can forward to the main part of the talk. Apparently on campus classes are going to be meeting as of this week - no word if he's going to record those.
"There are yahoos out there. It’s why we can’t have nice things." - Tom Mahood
"There are yahoos out there. It’s why we can’t have nice things." - Tom Mahood
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Brushbuffalo
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Location: there earlier, here now, somewhere later... Bellingham in between |
As a long time geology professor (43 years but retired for the past 6 1/2), I believe I can speak with some authority in highly recommending Nick Zentner as an informative, accurate, and entertaining teacher.
Passing rocks and trees like they were standing still
Passing rocks and trees like they were standing still
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reststep
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reststep
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Fri Mar 19, 2021 9:25 am |
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I was hiking up Mt. Walker last week and noticed this large boulder just off the trail. It appears to me to be granite. Must be a glacial erratic.
"The mountains are calling and I must go." - John Muir
"The mountains are calling and I must go." - John Muir
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Brushbuffalo
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Joined: 17 Sep 2015
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Location: there earlier, here now, somewhere later... Bellingham in between |
| reststep wrote: | | Must be a glacial erratic.
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Excellent. Although lithology isn't clear from the photo, it is probable that this is indeed a granitic boulder. The northern portion of the Olympic Peninsula is littered with clasts ranging from sand and pebbles to cobbles and boulders that were transported by continental glaciers from bedrock in British Columbia during the Pleistocene. Granite is abundant on mainland B.C. but absent as bedrock on the OP.
The erratic you found shows a couple of good facets , in erratics being the result of the rock being dragged along the base of the slowly moving ice and becoming flat, much as you get by rubbing a potato across a grater.
Ice was about 4500 feet thick in the Mt. Walker area based on upper elevation of erratics (4000' plus depth of Strait of Juan de Fuca (500'].
Passing rocks and trees like they were standing still
Passing rocks and trees like they were standing still
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klar
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klar
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Fri Mar 26, 2021 2:13 pm |
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Looking at photos from last summer and remembered this thread.
Interesting rock found below Circle peak in the North Cascades.
Any insights into the geology?
 vein
I wish I could write as mysterious as a cat. Edgar Allan Poe
I wish I could write as mysterious as a cat. Edgar Allan Poe
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coldrain108
Thundering Herd
Joined: 05 Aug 2010
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Location: somewhere over the rainbow |
about 5500' in the Olympics. Interesting scrape marks, the shadowing really brings it out.
Since I have no expectations of forgiveness, I don't do it in the first place. That loop hole needs to be closed to everyone.
Since I have no expectations of forgiveness, I don't do it in the first place. That loop hole needs to be closed to everyone.
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mike
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mike
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Fri Mar 26, 2021 5:57 pm |
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I have those in my front yard 
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Brushbuffalo
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Location: there earlier, here now, somewhere later... Bellingham in between |
| klar wrote: | vein |
The geology of the area surrounding and including Circle Peak is designated as the Nason Ridge Migmatitic Gneiss.Your picture appears to be an example of one of interlayered mica schist found in the Nason Ridge formation. Note the little 'ridges' and 'valleys' in your sample, which are the result of differential weathering between mica (valleys) and quartz and feldspar ( ridges).
The prominent white band is a vein that cross-cuts the host rock as a 3 dimensional plane, not a line as it appears in two dimensions if we look only at the front face. White veins like this are usually composed of quartz but in sedimentary rocks are often made of calcite. Since this vein cuts across the foliation of the mica schist, the vein is younger than the host rock.....possibly by a lot!
Passing rocks and trees like they were standing still
Passing rocks and trees like they were standing still
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Brushbuffalo
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Joined: 17 Sep 2015
Posts: 1887 | TRs | Pics
Location: there earlier, here now, somewhere later... Bellingham in between |
Although I can't identify the rock ( other than guessing it is a fine-grained grained sedimentary or low-grade metamorphic rock), the scratches are unmistakable glacial striations.
Can you give us a more precise location about where you took the picture?
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Passing rocks and trees like they were standing still
Passing rocks and trees like they were standing still
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klar
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klar
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Sat Mar 27, 2021 9:26 am |
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Cheers for the explanation! Did not realize how complex the geology was in that region.
I wish I could write as mysterious as a cat. Edgar Allan Poe
I wish I could write as mysterious as a cat. Edgar Allan Poe
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Anne Elk
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Anne Elk
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Sat Mar 27, 2021 1:10 pm |
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Brushbuffalo - You and this thread are a NWH treasure. 
Geology noobs such as myself looked at that Circle Peak sample that klar posted, and thought the "ridges and valleys" were sedimentary layers. That was one of the more interesting samples offered up in quite a while.
"There are yahoos out there. It’s why we can’t have nice things." - Tom Mahood
"There are yahoos out there. It’s why we can’t have nice things." - Tom Mahood
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Brushbuffalo
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Joined: 17 Sep 2015
Posts: 1887 | TRs | Pics
Location: there earlier, here now, somewhere later... Bellingham in between |
Thanks for the enthusiasm, Anne Elk.
Concerning klar's Circle Peak rock, note carefully the portion of the vein in the 'top' of the sample. We see a slight ridge where the vein has withstood weathering better than the host rock. That is true in the ' front' too but the relief doesn't stand out when we look straight on. Different materials change differently in the same environmental conditions (i.e. differential weathering)
A mini-lecture could be made just from these two examples of differential weathering in the same rock.
Oh wait, I suppose you just got it!😊
Passing rocks and trees like they were standing still
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