0 thoughts on “What are these geologists looking at?”
Hmmm. Well, they’re standing on a knob of bedrock that’s been overrun by the Athabasca Glacier (that’s its lateral moraine in the background). The bedrock around here is carbonates of Cambrian and/or Devonian age. So, I’ll guess–in order of likelihood: 1) Glacial striations and/or polishing; 2) Devonian tabulate corals; 3) Cambrian trilobites.
Nuts. OK, I cheated and did some reading, so I think I know what it is now, but I’ll let someone else have a kick at it. Suffice it to say (if I’m right this time) it’s something that would be of interest to structural geologists, and the evidence is visible in the photo.
You’re right that it is of interest to structural geologists, but I’d be shocked if you could make it out in this photo, given how far away the photographer was from the cm-scale features we were discussing.
Since you’ve given the clues about it relating to structural geology and it’s cm scale, my guess would be something showing that bedding is overturned, like ripple marks, or burrows or shell beds.
Nuts again. Maybe I should just shut up and wait for the answer, but I’m too weak to resist. I figured your group was standing on the fault trace of the (?)Simpson Pass Thrust. Looks like the rocks to the left of your group are dipping at a very different angle than those to the right of the guy in the orange shirt, in which case you would be looking at slickensides or something closely related. But maybe that’s just a trick of the camera angle and my imagination. If this isn’t related to the fault, then I’ll just toss out a WAG and say “stylolites”.
Photo by Sarah O.
Hmmm. Well, they’re standing on a knob of bedrock that’s been overrun by the Athabasca Glacier (that’s its lateral moraine in the background). The bedrock around here is carbonates of Cambrian and/or Devonian age. So, I’ll guess–in order of likelihood: 1) Glacial striations and/or polishing; 2) Devonian tabulate corals; 3) Cambrian trilobites.
Spoken like a man who knows the Canadian Rockies! But while we came for the glacial striations, we stayed for something else…
…and it wasn’t fossils!
Nuts. OK, I cheated and did some reading, so I think I know what it is now, but I’ll let someone else have a kick at it. Suffice it to say (if I’m right this time) it’s something that would be of interest to structural geologists, and the evidence is visible in the photo.
You’re right that it is of interest to structural geologists, but I’d be shocked if you could make it out in this photo, given how far away the photographer was from the cm-scale features we were discussing.
Since you’ve given the clues about it relating to structural geology and it’s cm scale, my guess would be something showing that bedding is overturned, like ripple marks, or burrows or shell beds.
Good guess — but it’s not primary structures that caught our eye…
Nuts again. Maybe I should just shut up and wait for the answer, but I’m too weak to resist. I figured your group was standing on the fault trace of the (?)Simpson Pass Thrust. Looks like the rocks to the left of your group are dipping at a very different angle than those to the right of the guy in the orange shirt, in which case you would be looking at slickensides or something closely related. But maybe that’s just a trick of the camera angle and my imagination. If this isn’t related to the fault, then I’ll just toss out a WAG and say “stylolites”.
WAG confirmed! Guess I should write the follow-up post now…