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Author Topic:   How do geologist know what they are looking at really is what they say it is?
Percy
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Posts: 20754
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.2


(1)
Message 14 of 88 (790295)
08-29-2016 7:56 AM
Reply to: Message 12 by Pressie
08-29-2016 6:43 AM


Pressie writes:

Economic geology. Old earth models work. In my case, the coal seams found in northern part of the Witbank Coalfield are very consistent with being deposited on deltas resulting from rivers flowing out of U-formed glacial valleys into a lake. And then the different types of vegetation forming the coal deposits and coal seams. And evidence for shore transgression and regression. Hence the different coal seams.

This would be interesting to understand better. What is it you find that tells you it was "deltas resulting from rivers flowing out of U-formed glacial valleys into a lake"?

--Percy

Edited by Percy, : Grammar.


This message is a reply to:
 Message 12 by Pressie, posted 08-29-2016 6:43 AM Pressie has replied

Replies to this message:
 Message 17 by edge, posted 08-29-2016 10:53 AM Percy has seen this message
 Message 38 by Pressie, posted 08-30-2016 6:27 AM Percy has seen this message

  
Percy
Member
Posts: 20754
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.2


Message 40 of 88 (790398)
08-30-2016 7:49 AM
Reply to: Message 33 by edge
08-29-2016 4:01 PM


Re: Great so far but I'm slow so humor me by expanding some.
edge writes:

Also you mentioned chemical and mechanical weathering in the context of the production of the sediment; but don't those processes also occur during and after lithification? And don't those characteristics give us clues as to the depositional environment?

Yes, however, the breakdown of rock to producing clastic sediments is kind of the opposite to lithification.

I guess I didn't understand the question. About chemical and mechanical weathering occurring during lithification, since lithification occurs after burial, how could there be any weathering? And about after lithification, can't weathering only occur after exposure?

--Percy


This message is a reply to:
 Message 33 by edge, posted 08-29-2016 4:01 PM edge has replied

Replies to this message:
 Message 44 by edge, posted 08-31-2016 6:35 PM Percy has seen this message

  
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