What is the Muleshoe Dune field?
The Muleshoe Dune Field is exactly what it sounds like – a
field of dunes near Muleshoe! Actually, it isn’t just near
Muleshoe but covers a much larger area. Stretching Eastward over
110 miles from near Tolar, NM to almost Hale Center, Texas, the
Muleshoe Dune field covers quite a large area. On satellite imagery
the Muleshoe Dune field looks like a big scar ripped across the
land.
Where did all of this sand come from?
According to Dr. C.C. Reeves of Texas Tech University’s
Department of Geosciences, “Green (1951) believed [the]
source of the Muleshoe dunes was the Pecos Valley and the
westernmost High Plains, but Jones (1959) and Hefley and Sidwell
(1945) suggested local streams and related floodplain deposits.
Because the Muleshoe dunes are confined to the Portales Valley, the
site of the last major Pleistocene stream flowing across the Llano
Estacado, and because of the regional absence of eolian
crossbedding and decrease in grain size from the central part of
the dune area (Jones, 1959), I also suspect the fluvial deposits of
the Portales Valley as the original source area.”
In layman’s terms: it is widely accepted that the sand of the
Muleshoe Dunes was deposited in the area around Roosevelt County,
NM by a stream or river nearly 12-13 thousand years ago and then
blown to its current location.
Features of the Muleshoe Dune field:
Blowouts – These occur in partially vegetated
dunefields and sandhills. A blowout forms when a patch of
protective vegetation is lost, allowing strong winds to "blow out"
sand and form a depression. Although they generally remain small,
blowouts can expand to kilometers in size and up to around 70m in
depth.
Yardangs – Yardangs are formed by wind erosion,
typically of an originally flat surface formed from areas of harder
and softer material. The soft material is eroded and removed by the
wind, and the harder material remains. The resulting patter of
yardangs is therefore a combination of the original rock
distribution, and the fluid mechanics of the air flow and resulting
pattern of erosion.
In order to log this Earthcache please send me an email with
the answers to the following questions:
- What other dune features can you spot? How do you think
these features were formed?
- Describe the makeup of the sand within this dune. Is it
compacted and hard to break apart or is loose and easy to
seperate?
- Do you see evidence of other types of erosion besides wind?
These can be biological, fluvial, or
mechanical.
Not required but strongly recommended - Take a picture of
you or your GPS at the coordinates with the dune in the background
and post it with your log.
Sources
"Blowout (geology)." Wikipedia.
Web. 08 June 2011.
<http://en.wikipedia.org/wiki/Blowout_(geology)>.
Reeves, C. C. "TERTIARY-QUATERNARY STRATIGRAPHY AND GEOMORPHOLOGY
OF WEST TEXAS AND SOUTHEASTERN NEW MEXICO."New Mexico Geological
Society.
Jan. 2008. Web. 6 June 2011.
<http://nmgs.nmt.edu/publications/guidebooks/downloads/23/23_p0108_p0117.pdf>.
Ritter, Dale F., R. Craig. Kochel, and Jerry
R. Miller. Process
Geomorphology. Long Grove, IL: Waveland, 2006.
Print.
"Yardang." Wikipedia.
Web. 08 June 2011.
<http://en.wikipedia.org/wiki/Yardang>.