Mark Schult (
Fri, 29 Aug 1997 18:00:55 -0400

There are many places that have terrestrial vertebrate footprints on
different layers. The one I am most familiar with lies near Las Cruces,
New Mexico. At the main quarry, 25 layers (based on the practical measure
of ability to remove a slab) were identified (if youâre on this list,
thanks again Jerry for all your work). Several layers could be split
further with more tracks visible (these were NOT undertracks as some
claimed). This one quarry with perhaps 2 meters vertical face exposed
could have had hundreds of laminae with different sets of tracks. The
rocks are mostly siltstones and very fine sandstones. The generally
accepted interpretation is that these rocks were deposited in the
intertidal zone in an area of relatively high tidal range. More
information (and disagreement) can be found in various papers ăEarly
Permian Footprints and Faciesä edited by SG Lucas & AB Heckert (NM Mus Nat
Hist Sci Bull 6).