Re: Terra Nova: thoughts

[David Marjanovic <david.marjanovic@gmx.at>]

>  I know that limestone didn't originate in teh Cretaceous, unless you
>  happen to live where it did. I don't think it's all that old
>  everywhere on Earth. Certainly not in Texas. Evidently all
>  pre-Cretaceous rock here is sandstone and shale. And occasional
>  granite. Also chert, but in isolated small rocks, and probably from
>  the same source as the limestone.
>
>  Back in the Adirondacks, most rock was granite, gneiss, quartz, and a
>  much older and harder sort of limestone, but you had to look for the
>  limestone, it was hardly 95% of the rock.

Over here, almost all limestone -- and there's lots of it -- is 
Triassic, and most of the rest is Permian. However, it was mostly still 
underwater in the Cretaceous.

Stromatolites are limestone, and in some places they're common enough to 
form entire formations. In short, there's billion-year-old limestone out 
there.