I’ve been so busy lately that I completely forgot to do a bit of research for a reader that e-mailed me a photograph of some interesting (and beautiful) rocks.
So, I decided to make it a geopuzzle and let the collective intelligence of the blogosphere discuss, debate, and ultimately solve.
Here is what the reader says about the rock in an e-mail to me:
The rock is about 4 feet across and is near the Martial Glacier outside Ushuaia, Argentina.
Alright … have at it!
UPDATE (6/23/09): This update was posted after the comments below to try and capture the general consensus on this particular geopuzzle. Everyone mentioned and admired the quartz ptygmatic folds (the white squiggly layer). Kim pointed out the parasitic folding — which, correct me if I’m wrong, is the term for the self-similarity of fold geometries of different wavelengths (note how the thinner layers are folded tightly within a longer-wavelength fold). In terms of what kind of rock this is, looks like most would agree that these were sedimentary rocks (evidenced by the layering) that were deformed (evidenced by the folding) and likely metamorphosed somewhat.
I have done some work in this general region and there are extensive outcrops along the Andean orogen composed of Paleozoic (~250-550 million yrs ago) meta-sedimentary rocks. While we can’t be absolutely certain that’s what this rock is just from this one photo … if I had to make the call, that’s what it would be. Or, another way to look at it … now we have a solid hypothesis to test. We just need to get down to Tierra del Fuego and sample this thing. Field trip!