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Old 04-29-2018, 11:09 PM   #37
Johnny1A.2
 
Join Date: Feb 2007
Default Re: Pre-human civilizations on Earth

Quote:
Originally Posted by malloyd View Post
Concrete is a conglomerate (it's got sand and little stones in it). Some cements are calcium carbonate, so marble would be plausible for those, but funny looking marble with all those inclusions. Most cements are calcium silicates and aluminates though, so probably feldspar for those.

Clearly the planet had some really *weird* depositional environments back when concrete formed as a sedimentary rock. Probably whatever produced all the volcanic ash that went into these deposits also contributed to the co-occurring Q-N mass extinction.
This is something I've thought about. Occam's Razor would cut badly in this case, if we did find remnants of a long-ago high society, it might take quite some time before we were prepared to accept that it was what it was, esp. if we only had a few pieces.
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