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Author Topic: What are these bands of black deposits within Devon sandstone?  (Read 611 times)

Offline Coolsmoke

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Hi folks,

I've just registered to post an email to ask for some help from any geologists out there.

My fiancee is building a house in the county of Devon UK.  As part of the groundwork, we had to excavate a hill and discovered some rather weird striations.

Among them are at least three layers of what appears to be peat.  It's oily, soft and brittle but I've blowtorched it and it doesn't burn.

Can anyone tell me what this stuff is?

Thanks in advance for you replies!
« Last Edit: 10/10/2016 19:38:54 by chris »


 

Offline Colin2B

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Re: A Puzzling Discovery..
« Reply #1 on: 10/10/2016 18:18:25 »
im guessing its a carboniferous shale. Is it inbetween sandstone?
 

Offline Coolsmoke

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Re: A Puzzling Discovery..
« Reply #2 on: 10/10/2016 18:40:15 »
From the little I know about Devon's geology, it's likely that the intervening strata are indeed sandstone - although they look like no sandstone I know of.

Thanks for your answer :)
 

Offline chris

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Re: A Puzzling Discovery..
« Reply #3 on: 10/10/2016 19:36:56 »
That sort of black material is carbon and can demarcate the route of an ancient river or watercourse. In these cases it originates from sediment deposited on the river bed.
 

Offline Bass

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Likely low-grade coal or carbon, but the other possibility is manganese oxide.
 

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