Re: preserving raindrops and mats

Arthur V. Chadwick (chadwicka@swac.edu)
Thu, 15 Jan 1998 09:50:35 -0800

At 08:55 PM 1/14/98 -0600, Glenn Morton wrote:
>Unfortunately, I quit saving the AAPG explorer about 2 years ago. Now I
>regret it. I remember that photo but a water escape structure might not be
>unexpected given certain environments which are found in the Navajo.
>
> "Recent work shows that the Navajo is indeed a classic
>desert sand dune deposit. Locally, however, can be found
>evidence for small oases or playa lakes represented by
>distinctive thin layers of grayish limestone that often contain
>reveal tracks. Although rare, the Navajo has also yielded
>skeletal remains of crocodilians (a small primitive Protosuchus-
>like crocodilian), mammal-like reptiles known as trytylodonts,
>and dinosaurs including the chicken-sized theropod Segisaurus and
>the small prosauropod Ammosaurus."~Martin Lockley and Adrian P.
>Hunt, Dinosaur Tracks, (New York: Columbia University Press,
>1995), p. 130
>
>Escape structures in the playa deposits would not be unexpected.

Yes, but it is tautologic to assume a playa lake to explain the
deformations then to say there was a playa lake and that explains the
deformations. Let's look for independent evidence for a playa lake at the
locality in question that is not based on the presence of dewatering
structures.
Art
http://chadwicka.swau.edu