Geopuzzle: Cheshire Cat


I’d actually hoped to write this one up myself, but Lockwood beat me to it. Here’s the Cheshire Cat puzzle Aaron and I solved on the Quartzville trip. Think you can find the answer faster than we did?

Smile If you Like Earth Science Week: Cheshire Cat! (Clues 1 & 2)

Cheshire Cat! Clue 3 for the Puzzle

Cheshire Cat! Clue 4

Cheshire Cat! Clues 5 and 6

Good luck!

Aaron and Lockwood discussing the Cheshire Cat.

Cheshire Cat outcrop panorama. Best I could do with all the alders in the way. Sorry.

Comments

  1. Trebuchet says

    Hmmm…

    I’m pretty well clueless on this stuff. Perhaps one flow on top of the other, with the older, lower one made of some sort of viscous lava which flowed over a depression in the ground, matching its contour. That was then perhaps filled in with some earth. The newer one then went over the top of everything. When the quarry was excavated, the softer material between the flows washed out, leaving the smile.

    Meanwhile, I saw some awesome geology yesterday, driving the entire length of the Grand Coulee from South to North and back. What a place.

  2. rq says

    I’m clueless about geology, too, but I read through all the clues and looked at all the maps and read the road diary and everything, including Lockwood’s continued references to other clues and subtle hints and things that he has mentioned but not directly. I doubt this will count as a full answer, but I felt compelled to try because both quartz and granite are very dear to me – having grown up on a piece of the Canadian Shield (literally – our house didn’t have a basement because it stood on a bare slanted rock face), and near old mica quarries (where we often went to pick out large pieces of apatite and quartz from the refuse piles)… Enough of the nostalgia.
    I’m not sure how to put all this together into a coherent geologically meaningful answer, but what should be on the other side of the road is a flatter plateau of bare rock with quartz veins running through it (I suppose somewhat perpendicular to the road, considering the direction of the Cheshire cat proposed 3D projection).
    Sooo… As for timing of events which Lockwood requests – my guess is something like – magma cooling into granite with quartz veins, followed sometime later by the lava flow that solidified rather quickly into the Chechire cat-type formation, covering some expanse of the granite layer (my wikipedia tells me that granites can form in a ring of hills or mountains). Then, over time, the basalt has eroded, in some places somehow finding a way to erode through the harder layer (maybe where there were already indentations, then eroding through the basalt in those indentations) to create the cooling vents. And also some vertical(ish) quartz outcroppings.
    But yes, basically some flat rock with quartz veins.
    And that’s my wild guess.

  3. lockwooddewitt says

    “Cheshire Cat! Clue 7 and a Question” is up at OTI. http://outsidetheinterzone.blogspot.com/2012/10/cheshire-cat-clue-7-and-question.html

    There is a lot of quartz-veined rock in the area around the quarry, and my clue this evening will show a crude sketch of how the basalt of the quarry sits in relationship to that material. Along with the end of the flow, you *can* see that rock in the creek bed and banks, but that’s not the feature I’m after.

  4. rq says

    Okay. I’m going to miss clue 8 due to time zones, but I looked at clue 7 and I’m going to take another guess for fun.
    At first glance (at smaller picture size) the columns look like they’re bending (coming out of the wall and bending downwards), but. Could it be that the lower layers cooled more slowly, while the higher layers cooled more rapidly? (I’m not finding too much information on orientation and stuff, and my time is rapidly ticking away, so that’s another wild guess.) The orientation seems to vary through the Cheshire Cat smile, with the thicker columns in the middle, meaning… a lava flow thicker through the middle?
    Annnd… If I take the hot-to-cold idea right to the end, I have a bit of a question: can lava flow under ice without blowing it away completely? Because the real wild-guess bit would be something like a thick lava flow under ice (during an icy period?), with the top cooling off quickly and the bottom slowly. Alternatively, what with the river/creek and all, the lava may just have flowed through/into some water, cooling more rapidly and creating… pillow basalt? Which means the feature to be looked for on the other side is pillow basalt in the shape of boulders…?
    Taking the names of the surrounding area into account (Quartzville – that’s the quartz already mentioned/discounted; Gravel Pit – from the quarry, presumably either refuse or a pit from which gravel is dug because small-crystal rapid-cooling basalt on the top (?)), I am left with the newly-mentioned Boulder Creek – although, if there’s a lot of granite and quartz and all that around, chances are there are just large boulders around too.
    Okay, this wasn’t a whole-hearted attempt (but a day of walking will do that), but I’ll look in tomorrow for clue 8 and maybe another guess and at the very least some answers/rebuttals to my wild guesses!

    • lockwooddewitt says

      Yes, the flow *is* thicker in the middle. You’re getting awfully close, but I have no reason to think this was affected/influenced by ice at the time of eruption, and I’ve not seen any pillow basalt in this area. However, I think you’re on the right track. There is a key place name I’ve avoided mentioning in the clues so far, but it’s related to why I brought up Boulder Creek for clue 7. I spent some time last night trying to think of a few more clues that wouldn’t be dead give-aways, and clues 7 and 8 were ones I came up with. Clue 8, incidentally, is now finished and set to auto-post at 5:00 PM PDT.

  5. rq says

    By the way, if googling ‘cinder cone deposits’ under images, that photo of Dana by the vent shows up on the first page of photos. :)
    Trying to work out a new guess with the new clue. I think I’m hitting a wall, though – I have a feeling this would be a lot clearer if I had a better geology background and if I was on-location with all the other detailed introductory remarks fresh in my mind.

  6. rq says

    Okay, next guess – or a summary of things that I think I know but can’t put together. If I’m on the right track, I’m assuming that it’s a basalt formation of some kind. I’ve been looking through some of the place names in the area, and I’m not coming up with anything in particular – a bunch of mining sites, prospects, tunnels, gravel and lots of quartz. So either I’m missing something, or it’s so obvious I can’t see it. A couple of mountains named after cows and bulls, but that doesn’t seem to relate to geology directly (except perhaps colour of rocks in the area).
    So that gives me volcanoes and cinder cones and lava flow with slow cooling, which leads to basalt and various basalt formations. The trip log mentions Liesegang rings, which form under certain types of crystallization, but they’re mentioned as part of a different location (Red Heifer Pass).
    And then I found this photo:
    http://aaron1013.smugmug.com/Portfolio/New-Photos/3234585_CvCvHS/1334091737_XZgB9Cb#!i=1334091737&k=XZgB9Cb
    It’s in the right area (Western Cascades? Yes?), and it’s a basalt formation. So I’m throwing it out there, because it appears to be a view down into a creek.
    (Also, this go-round, I realized I’d been continuously looking at the wrong side of the road in maps for clues about the appearance of what’s on the other side, hence all those flat rocks with quartz veins and everything. This time I actually read the question at the end of clue 8 correctly and looked the other way.)

    I think I’m just not making a very important connection somewhere. Oh well. :) Waiting for more guidance.

  7. rq says

    Ok. I just had some nice answers that needed an expert eye, and… well, I won’t curse in public. At any rate, there are apparently other things I’m supposed to be doing this Sunday, so I’ll return later hopefully with those same answers.
    This time away will also let the new information settle a bit and perhaps I’ll come up with the brilliant solution.

  8. Eskered says

    The hackly jointing basalts appear to have flowed down a stream channel from the cinder cone at Mile 24.2. Maybe the columnar jointing is from a second cinder cone across the road that ran cooler and backflowed up the channel before being buried by additional flows from the Mile 24.2 cinder cone.

  9. lochaber says

    Lava flow down a stream channel?

    The portion near the bottom cooled rapidly due to water presence, and the top part cooled rapidly due to atmospheric exposure, giving the hackly jointing.

    The inner part of what filled the channel was somewhat insulated, allowing it to cool slow enough to form the columnar jointing, but leaving a profile similar to the channel.

    I wasn’t a good student when I studied this, and that was a long time ago.
    Maybe I should look into trying to take some courses piecemeal, at least for the fieldtrips, if nothing else. I miss those.

  10. Eskered says

    Alders would indicate a water source. Maybe groundwater seepage near the base of the outcrop through the older altered rock below. Possible outflow of Dry Gulch drainage during drier months?

  11. lockwooddewitt says

    And Bingo! We have a winner! It’s more than seepage, it’s a full blown spring, with a volume of many gallons per second, but Eskered hit the important location name, Dry Gulch, and the important idea, which is that Dry Gulch is *dry.* As I pointed out in Clue 7 yesterday, a nearby drainage with a smaller basin has year-round flow, so one would expect the Dry Gulch basin would as well. But I’ve *never* seen surface flow in Dry Gulch- and I alluded to that in the road log. So the question is, “where’s the water, and where’s it going?” And the answer is, except during periods of extremely high runoff, it’s still following the ancestral drainage which was buried by the cinder cone, and the lava flow that formed the Cheshire Cat quarry.

    I have a couple pictures, taken through too much foliage, of the spring, but from previous visits, I can tell you that the springs come out through a distinct layer of rounded cobbles, which I take to be buried sediment in the ancestral Dry Gulch channel.

  12. rq says

    Yes, I read the newest clue. And what I previously had (using Dana’s questions as a guide) leads much to the same thing – water on the other side. To answer Dana’s questions (which I had answered previously but computers):
    1) Quartz forms through precipitation from aqueous solution (the veins), meaning there’s lots of water in the area.
    2) The direction of the columns indicates a short cooling front on top and a curved concave cooling front on the bottom (from the cross-section) – the hackly jointings indicate faster cooling, while flow through the creek bed allows for the formation of thicker lava flow down the middle, as Eskered mentions, which is more insulated and thus cools slower.
    3) The hackly jointings on the bottom indicate that there was a cooling front on the bottom, not only on the top. So, probably water in a creek bed of some kind.
    4) Stream + lava flow…. ? Meaning, looking down into the stream, there is an overgrown old lava flow joining up with the stream? With… lots of gravel and hackly jointing materials annnd… See, this is where I get lost. There’s a connection I’m supposed to make here, but I just can’t visualize it (lack of knowledge and field experience). I know it’s there, and since it’s so close and so obvious…

    Alders = water source, different soil type than the surrounding evergreens (from what I get in the pictures). That much I got right away. I see it here all the time – pine forests all around, but with occasional copses of birches, meaning water/swampy area, meaning more fertile earth, rather than the sandy earth favoured by the pines. And again, I’m not sure what the connection here is. Basalt columns – with hackly jointings eroded away – going into the stream? Or with the elongated bits going into the stream? (Alders also fixate nitrogen…)

    What I ideally picture (especially after Dana’s rock interior design post) is hexagonal tiles with quartz in between and veins of gold. Black, white and gold – what a floor that would make! So, I’ll admit that I’m stumped. Lockwood says we’re close – but there’s something I’m missing, some singular element or word or term that maybe I’m thinking of but not identifying. It’s frustrating; I hope somebody comes up with a brilliant answer!

  13. Eskered says

    If this outcrop infilled the ancestral Dry Gulch drainage, maybe the columnar jointing represents the drainage still trying to use the channel, before being overrun by basalt flows, forcing Dry Gulch to its current location to the north. If this were the case, you should see indications of stream outflow deposits below the basalt flows across the road.

  14. rq says

    That’s what I get for writing a long comment, although I still don’t mention the actual feature looked for. Too focussed on the lava flow…
    And yes, I did think about Dry Gulch quite a bit, but did not make the connection. Yay Eskered!

  15. rq says

    Actually I was close with the mention of the birches, because I was going to mention how here they sometimes grow in low-lying areas where ground water seeps through, even though there is almost no actual surface water nearby (not in the forest, anyways – some small ditches and a couple of ponds and a lake further off). I think it’s good that Eskered finished the puzzle, though, because me writing that might have caused Lockwood a lot more brain pain. *sigh* I’ll admit I’m a little bit bitter, but just a little bit, mostly because I spent a lot of time trying to figure this one out. But I WAS stuck at the end. So it’s ok. :) I’ll blame it on being a geology newbie. :)