Including Original "Paul H. Letters" Copyright © 1996-2017 Paul V. Heinrich - All rights reserved.



Thursday, 6 January 2011

Impact Crater in New Mexico – Part 1 Lea County

Impact Crater in New Mexico – Part 1 Lea County


About an area in Lea County, New Mexico, Abe wrote: 

“I plan to go on another meteorite hunting trip to New Mexico
soon before the Tucson show. Would you guys think that this 
is an impact crater? 32°21'54.39" N 103°23'47.50" W. I 
remember reading about it on a site but it appears that there 
are just too many craters in the area to all be impact craters. 
If they aren’t impact craters what would be the possibility 
they are ancient ponds for wildlife? I would imagine that as 
West Texas and New Mexico dried up, any remaining wet 
ground would become extremely populated with wild life 
and over centuries these locations would become deep ponds.”

These are playa lakes. They are neither impact craters nor 
related any type of impact processes. Some of these playa 
lakes have been  in existence throughout the Pleistocene. 
However, there is one known exception to how playa lakes 
typically form, it is the playa lake that occupied the Odessa 
impact crater.

About playa Lakes, Holliday et al. (1996) states

“These lithostratigraphic and chronostratigraphic
relationships show that some basins have a prolonged 
history as depressions, persisting in more or less the 
same location as the High Plains surface aggraded by 
eolian addition (Blackwater Draw Formation) throughout
the Pleistocene. Sizes of the basins varied through time as 
they were encroached upon by the Blackwater Draw 
Formation, enlarged by fluvial, lake margin, and eolian 
erosion, were filled and reexposed, or were buried. 
Some basins are newly formed on the High Plains 
surface and have no apparent predecessors.”

About the origin of playa basins, Gustavson et al. (1995a) wrote

“The initial formation of playa basins involved many 
processes but most likely started with collection of runoff 
in small, irregular topographic depressions on the High 
Plains. Initial depressions may have resulted from surface
drainage, dissolution of the Caprock calcrete, subsidence 
caused by salt dissolution, differential compaction, animal 
wallows, or blowouts where vegetation was missing. 
Ponded runoff killed vegetation or inhibited plant growth 
and allowed deflation to remove some of the surface 
sediment when the pond dried out. As the initial small 
basin expanded, fluvial erosion and lacustrine sedimentation 
became more important. centripetal drainage enlarged the 
basin by eroding the basin margin and carrying sediment 
to the basin floor. Periodic flooding continued to keep the 
center of the playa basin relatively clear of vegetation. 
Wind deflated dry sediment from the playa center. 
Deflation may have been accelerated after large herds of 
bison pulverized dried surface soils and carried small 
amounts of sediment out of the basin on their hooves. 
Sediments deflated from these basins were carried 
downwind.”

Some Publications About Playa Lakes

Gustavson, T. C., V. T. Holliday, and S, D. Hovorka, 1995a 
Development of Playa Basins, Southern High Plains, Texas 
and New Mexico. In Proceedings of the Playa Basin 
Symposium, edited by L.V. Urban and A.W. Wyatt, pp. 5-14. 
Texas Tech University, Water Resources Center, Lubbock.

Gustavson, T. C., V. T. Holliday, and S. D. Hovorka, 1995b 
Origin and Development of Playa Basins, Sources of 
Recharge to the Ogallala Aquifer, Southern High Plains, 
Texas and New Mexico. The University of Texas at Austin, 
Bureau of Economic Geology Report of Investigation 229.

Holliday, V. T., T. C. Gustavson, and S. D. Hovorka, 1996, 
Stratigraphy and Geochronology of Playa Fills on the 
Southern High Plains. Geological Society of America 
Bulletin. vol. 108, no. 8, pp. 953-965.
Abstract at http://gsabulletin.gsapubs.org/content/108/8/953.short
 

PDF file at http://www.argonaut.arizona.edu/articles/holliday_etal1996.pdf
 

and http://www.argonaut.arizona.edu/holliday.htm
 


Hovorka, S.D., 1997, Quaternary evolution of ephemeral playa 
lakes on the Southern High Plains of Texas, USA: cyclic 
variation in lake level recorded in sediments. Journal of 
Paleolimnology. vol. 17, pp. 131–146.
http://www.springerlink.com/content/u20316917821568q/
 


Osterkamp, W. R. and W. W. Wood, 1987, Playa-lake basins 
on the Southern High Plains of Texas and New Mexico: 
Part I. Hydrologic, geomorphic, and geologic evidence for 
their development. Geological Society of America Bulletin.
vol. 99, no.2, pp. 215-223.
http://bulletin.geoscienceworld.org/cgi/content/abstract/99/2/215
 


Wood, W. W., and W. R. Osterkamp, 1987, Playa-lake basins 
on the Southern High Plains of Texas and New Mexico: Part II. 
A hydrologic model and mass-balance arguments for their 
development. Geological Society of America Bulletin.
vol. 99, no.2, pp. 224-230.
http://bulletin.geoscienceworld.org/cgi/content/abstract/99/2/224
 


Playa lakes are an extremely important to local wildlife as
the primary wetlands in this part of the southern High Plains
as discussed in:

Haukosa,  D. A., and L. M. Smith, 1994, The importance of 
playa wetlands to biodiversity of the Southern High Plains.
Landscape and Urban Planning. vol. 28, pp. 83-98.
http://dx.doi.org/10.1016/0169-2046
 
(94)90046-9

Smith, L. M., 2003, Playas of the Great Plains. University of 
Texas Press, Austin, Texas. 275 pp. ISBN: 978-0-292-70177-9
http://www.utexas.edu/utpress/books/smipla.html
 

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1781&context=greatplainsresearch
 


Yours,

Paul H.

No comments: