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Geology/rock identification


Oval Rock
Oval Rock  
QUESTION: I have this rock that was found in Western Pennsylvania many years ago. Can you identify it for me? It just appeared in our yard one day when I was a child. It is dark brown in color with a few pock marks. It is mostly smooth in texture. I have attached a picture.


Where in western PA?  It looks like a concretion out of the shales around Altoona/State College.

Give me a little more detail on where it came from and I can try to give you a better guess.


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QUESTION: The biggest city is Sharon, Pennsylvania.

ANSWER: Well, heck, that's nearly eastern Ohio!  I think it is some sort of sedimentary rock, mostly because the photo seems to suggest there are layers.  It is rounded because it has been subjected to erosion and weathering by water.  Given those two facts and the color, it is probably a well cemented sandstone or siltstone.  The pits or pockmarks are where larger mineral fragments have been knocked out during the weathering process.

of course, this is all from looking at one photograph and some limited geographic information.  I could be completely wrong, but I think the story above is credible!

Hope this helps.



---------- FOLLOW-UP ----------

QUESTION: Is it odd that it is perfectly oval? It was not found in a creek. It was found just laying out in the back yard one day.

Its not particulary odd.  Its odd that it would be in your backyard....  we would have to think hard about how it got there.  Someone might have dropped it, someone might have buried it there and it worked its way to the surface......  lots of possibilities.



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Fraser Hamilton


I have over 15 years of professional experience in the environmental geology field. I am well versed in general geology types of questions and answers. In addition I have a keen understanding of physical stratigraphy (especially in the Valley and Ridge of Central PA) and cycles.


Eight years of education, fifteen years of professional experience. Have worked or studied in ME, PA, TX, KY, IN, TN, OH, WA and Scotland.

Geological Society of America
American Association of Petroleum Geologists
Properties Magazine
Cleveland Bar Association
Cleveland Engineering Society

BA Geology/Math, University of Maine at Farmington
MA Geology - Physical Stratigraphy, Temple University
Post Grad Studies Geology - Texas A&M University

Awards and Honors
Distinguished graduate teaching award, Temple University

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