[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Archies in the Morrison?!

>       You read my mind!  I would _LOVE_ to find some nice lithographic 
> limestones of Late Triassic/Early Jurassic age somewhere!  And,if they 
> _don't_ exist anywhere, barring complete erosion, could anyone suggest a 
> reason why they _don't_ occur in those time periods?  (Barring lack of 
> exposure, too...)

If I understand my historic geology right...during the Late 
Triassic/Early Jurassic most of the continents lacked epi-continental 
seaways and off shore shelves were quite narrow and deep.  Also this time 
was marked by a lot of rifting...great for evaporates but lousy for those 
calm, shallow lagoonal deposits.  
I suggest a better source for small vertebrates are the playa deposits 
and fine grain mud deposits (mudflats---great for footprints).

---John Schneiderman (dino@revelation.unomaha.edu)