Monday, May 18, 2009

Hidden Gobi

As part of a weekend trip out to eastern Umnugovi Aimag with friends from Khankhongor Soum, the school driver from Khanbogd Soum (a mutual friend) led our group out to an interesting geological formation about 30km from the soum center. He emphasized to me several times that few people knew about the place, and everyone in the Khankhongor contingent confirmed this by repeating several times they had never even heard of the place let alone had visited it previously.

I am not a geologist, so I could only marvel at the site and wonder how it was formed. The rock looked like a cross between granite and crystalline concrete. It was very rough and it easily broke under modest pressure. It looked as though the rock formed initially under a sedimentary process, and then later the area was shaped by some sort of erosive force. I was compelled based on intuition and knowledge barely remembered from a geology class I took over ten years ago in college to think that it formed under the influence of water. It had several hallmarks of water erosion, especially pock marks born into the sides of boulders. But, that would suggest that a very large sea or other body of water with currents was present at the location at some point in its history, and I am not sure if there was such a body of water in the Gobi. The hypothesis therefore has an obvious flaw, and I remain ignorant of the true cause of the formations.

If there are any geologists out there reading this with ideas, please do offer comments. It was a truly interesting place.

3 comments:

Laurel Fan said...

I am not a geologist either, but since it is in the Gobi I would guess that wind erosion could be the cause.

Brian White, ACMS Resident Director said...

Yeah, that is something I also considered, and that was an explanation one of the teachers with us gave for the interesting erosion patterns. Maybe I dismiss it way too easily, but my intuition tells me that wind is not strong enough to erode that kind of rock. It was not sandstone, but more like concrete. Moreover, it seems somewhat weird that eddies would form often enough in one spot to bore holes into the rock over presumably many, many years.

But, it would make it even more intriguing if in fact wind can have such an erosive effect and eddies and vortexes form often and consistently enough to actually bore through rock over time. It would make the place that much more amazing to me for sure.

S.L. said...

Brian: That place looks pretty cool. I would have to see it to make a determination, but the formations are incredible. Any rodents around there? -slg