| Previous :: Next Topic |
| Author |
Message |
zephyr
aka friendly hiker
Joined: 21 Jun 2009
Posts: 2461 | TRs
Location: West Seattle
|
| NorthBen wrote: |
| A friend fished these out of the Sauk River. Any guesses on rock type and fossil species? |
Man, those are some beautiful rocks. ~z
.
. |
|
| Back to top |
|
|
Mike Collins
Member
Joined: 18 Dec 2001
Posts: 2810 | TRs
|
|
| Back to top |
|
|
NorthBen
Member
Joined: 29 Feb 2012
Posts: 48 | TRs
|
Another friend-of-a-friend geologist also thought the "harmonica" was a crinoid, with the more circular fossils also being crinoids rotated 90 degrees and viewed head on.
I've seen crinoid fossils in Death Valley several years ago and remember getting the impression they're pretty common as far as fossils go:
|
|
| Back to top |
|
|
Brushbuffalo
Member
Joined: 17 Sep 2015
Posts: 1721 | TRs
Location: there earlier, here now, somewhere later... Bellingham in between
|
| Mike Collins wrote: |
| the “harmonica” is a portion of the stem/column of a crinoid. |
Mike and Ben, I initially had 'crinoid' as a possibility in my response, but deleted it. You guys are more 'paleo' than I am. 
--------------
Passing rocks and trees like they were standing still |
|
| Back to top |
|
|
zephyr
aka friendly hiker
Joined: 21 Jun 2009
Posts: 2461 | TRs
Location: West Seattle
|
The stalked forms are known as Sea Lilies, the unstalked ones are Feather Stars. They are still with us today. Here's a cool drawing by Ernst Haeckel via Wikipedia. ~z
Here's an interesting fossil form.
. |
|
| Back to top |
|
|
mike
Member
Joined: 09 Jul 2004
Posts: 6134 | TRs
Location: SJIsl
|
One of the most studied rocks in the world.
(file name is an incorrect description) |
|
| Back to top |
|
|
Malachai Constant
Member
Joined: 13 Jan 2002
Posts: 14882 | TRs
Location: Back Again Like A Bad Penny
|
Lots of Crinoids in Grand Canyon esp North Rim
--------------
"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn |
|
| Back to top |
|
|
Brushbuffalo
Member
Joined: 17 Sep 2015
Posts: 1721 | TRs
Location: there earlier, here now, somewhere later... Bellingham in between
|
Is that a question?
I am guess it's one of the major unconformities that led to the early study of geology as a science, so it's probably in Europe, maybe in Scotland and studied by Hutton.
--------------
Passing rocks and trees like they were standing still |
|
| Back to top |
|
|
mike
Member
Joined: 09 Jul 2004
Posts: 6134 | TRs
Location: SJIsl
|
| Yes Scotland but not Hutton's Unconformity. Wish I could have visited Siccar Point. This is the Moine Thrust at Knochan Crag. First documented evidence of horizontal movement so not an unconformity as generally described. Oldest rock is thrust on top by tectonic forces as shown by Peach and Horne. |
|
| Back to top |
|
|
Anne Elk
BrontosaurusTheorist
Joined: 07 Sep 2018
Posts: 1299 | TRs
Location: Seattle
|
This thread got bumped up; I was offline most of August and missed this:
| texasbb wrote: |
Okay, got a landform question. What mechanism formed the dozens of tiny little islands here?
Marshy upper end of Swamp Lake, Wallowas
Hi-res |
To which
| Brushbuffalo wrote: |
Based on your pictures, I think you have an example of a bio- geological runaway feedback loop. Let me explain the theory that I have.
Sediment, mostly gravel, accumulates in a braided stream channel during times of lessening flow velocity. If the little bars remain slightly above average water level, plants are able to become established. These plants trap more sediment thereby increasing the size of the mini islands, which facilitates more plant life on them...a runaway process by trapping more sediment and increasing the island size up to a point limited by erosion.
Key to this is in a gravel- rich stream channel we find that braiding is the dominant pattern, which causes bars to form separated by many divergent/ convergent channels (called ' anastomosing channels' by hydrologists). I have another theory....theory the second. And it's mine.(how about that, Anne Elk?) |
But after seeing this -
Google Earth view of the marshy inlet to Swamp Lake
| Brush Buffalo wrote: |
| I agree, it is not clear to me now after seeing that Google Earth image that these little islands are related to a braided stream pattern. The origin is probably at least as much biological as hydrological, but right now I am stumped. |
I like the anastamosis idea, BB (what a great word!), and your sediment trapping theory. But the photos reminded me of an arctic land formation I recently discovered wandering around Wikipedia: Pingo (Another great word!) Obviously there's no permafrost in the Wallowas, but perhaps those little round hummock formations in the anastamoses get further pushed upward by frost heaving in what looks like shallow, but permanent swamp (see the diagram in the Pingo article), providing more opportunity for plant colonization, contributing to the cycle. So there you have it: anastamosizing frost-heave pseudo-pingo feedback loops! (Maybe I should stick to brontosaurus theories). 
--------------
"There are yahoos out there. It’s why we can’t have nice things." - Tom Mahood |
|
| Back to top |
|
|
puzzlr
Mid Fork Rocks
Joined: 13 Feb 2007
Posts: 6772 | TRs
Location: Stuck in the middle
|
This thread is so great. I wish I could contribute! I spend a lot of my time on hikes asking "why" and "how" questions about the land forms around me. Sometimes I know, but mostly just wonder.
--------------
Mid Fork Rocks • flickr |
|
| Back to top |
|
|
Brushbuffalo
Member
Joined: 17 Sep 2015
Posts: 1721 | TRs
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 |
|
| Back to top |
|
|
Brushbuffalo
Member
Joined: 17 Sep 2015
Posts: 1721 | TRs
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 |
|
| Back to top |
|
|
texasbb
Misplaced Texan
Joined: 30 Mar 2009
Posts: 1036 | TRs
Location: Tri-Cities, WA
|
| 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.  |
|
| Back to top |
|
|
Anne Elk
BrontosaurusTheorist
Joined: 07 Sep 2018
Posts: 1299 | TRs
Location: Seattle
|
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 |
|
| Back to top |
|
|
|
|
