Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: OokieWonderslug on 28/02/2011 21:45:39
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I was in WV recently and came upon this hill. It had tan mud and sandstone blocks interspersed throughout. There was mostly tan mud. In the midst of this mud was a rock unlike any of the others around it. It was a sandstone, but not the hard, fine grained sandstone that is normal for this area. This sandstone was still sandy. And black! One large bowling ball sized black rock in a cliff of tan mud. I climbed up on the hill to investigate and the rock was extremely crumbly. A large part broke off in my hand. I then noticed that embedded in the rock were smaller hollow rocks. Lots of them. At first I thought they were fossilized nuts of some kind. But they were different shapes and sizes. Some broke apart upon touching them others seemed harder. I scraped away all the black sandstone and was left with a few marble sized rocks that are hollow inside. When I shake them I can hear the debris moving around. The broken ones had a little yellow mud inside. Most were empty.
I can't figure how this rock formed nor the hollow rocks it contains. Why only one black rock of this type there? Why didn't it form a solid stone when the sand above and below it did? Why was it embedded in a hillside of tan mud? How do you get random hollow stones inside a rock like that? When I first got them out of the rock, they had a metallic sheen to them. And there was what appeared to be some rust inside the black sandstone too.
The broken stones had a dark brown shell that was very fine grained. It came from a hillside in Princeton, WV where the sedimentary layers go from a 45 degree angle to level. In the level sediments. About 10 miles from the angled ones.
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any chance of a picture? Your descriptions are great, but it could be a number of things.
Do you know the name of the formations?
Sounds most like weathering of different rock type in the sandstone/mudstone. Possibly a pyrite or other concretion? Weathering would account for the voids and soft nature of the black rock.
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No pics. The rock fell apart in my hands and I had no camera at the time. I do have the little nodules that were in the rock itself, but I don't have a camera to take any pictures with. That is why I tried to be so descriptive in my post.