Making Tracks

Here are a couple items about some recent finds of dinosaur tracks.

First: Check out the report of a find of dinosaur tracks along with the
imprint of a squatting dinosaur's posterior at

<http://story.news.yahoo.com/news?tmpl=story&u=/ap/20040326/ap_on_sc/dinosaur_tracks_2>
or
<http://www.sltrib.com/2004/Mar/03262004/utah/151299.asp>

Second: Many ASA'ers who attended last year's Annual Meeting in Lakewood,
Colorado visited the Dinosaur bone and track sites on Dinosaur Ridge just
west of Denver. (A map of the main track site inside the fence can be seen
online at <http://www.dinoridge.org/TrackMap.htm>). In a recent article
printed in the Friends of Dinosaur Ridge 2003 Annual Report, Martin Lockley
reported that this site is just one of 40 known dinosaur track sites
exposed at the same stratigraphic level in the Dakota Group sandstones.
The really interesting part though, is that these 40 exposed sites are
found scattered from northern Colorado south into central New Mexico and
from the Rocky Mountain foothills on the west eastward to the southeastern
Colorado border with Kansas. All 40 of these site also contain the same
suite of dinosaur trackmakers - Ornithopods (like Iguanodon) and Theropods
(like Coelurus). The main track site exposed at Dinosaur Ridge is an area
of about 4000 sq. ft. and has over 300 individual tracks. However, one
site at a reservoir in the Arkansas Valley (exposed recently by drought
conditions) reveals thousands of tracks over an area of several square
miles! Since this same dinosaur track suite has been found almost
everywhere that this particular sandstone layer of the Dakota Group is
exposed, Lockley and fellow researchers are suggesting that we have a
nearly continuous track layer (on the order of 5 to 10 meters thick)
covering an estimated area of forty to fifty thousand square miles. This
is, of course, a scientific prediction that will be tested as they search
for more exposures. Similar exposures of sandstone layers containing the
same suite of track makers have also been found in Texas and in eastern
Kansas, Nebraska, and Iowa. But these sites are not included in the
megatracksite (yes, it is one word) estimates above since they occur in a
different formation (although thought to be the same age) that apparently
formed on the other side of the mid-continent Cretaceous seaway.

In my mind, the tremendous number of known tracks alone (even if we ignore
any potential for megatracksites extending for 10's of thousands of square
miles) is a huge and largely-ignored problem for the YEC flood geology
crowd. The Cretaceous-age Dakota Group is in the middle of the sedimentary
package that is proposed to be deposited by the Global Deluge. (See also
my earlier post about the sequence of geologic events in Colorado at <
http://www.calvin.edu/archive/asa/200101/0154.html> where these Dakota
Group sandstones and tracks are represented as event 9 out of 14.)

Although I freely admit that it is a personal argument from incredulity, I
have a hard time accepting YEC theories such as those that would call for
herds of Ornithopod (herbivore) and Theropod (carnivore) dinosaurs
surviving together halfway through the incredibly violent, year-long Global
Deluge on floating mats of vegetation (which are continuously shedding
material to form extensive coal beds as Steve Austin and Bill Payne
propose); docking long enough to trample some thousands of square miles of
sands on the western shore of the sea covering the middle of North America;
re-embarking on their vegetation rafts and sailing south-eastward to
disembark and again trample the beaches on the eastern shore before finally
succumbing to rigors of the Flood. (With apologies to my YEC friends; I
simply couldn't resist the opportunity to paint this humorous picture
resulting from a combination of some of their ideas!)

Steve
[Disclaimer: All thoughts and opinions expressed herein are my own and are
not to be attributed to my employer.]
_____________
 Steven M. Smith, Geologist, U.S. Geological Survey
 Box 25046, M.S. 973, DFC, Denver, CO 80225
 Office: (303)236-1192, Fax: (303)236-3200
 Email: smsmith@usgs.gov
 -USGS Nat'l Geochem. Database NURE HSSR Web Site-
  http://pubs.usgs.gov/of/1997/ofr-97-0492/
Received on Mon Mar 29 11:34:41 2004