Mesas or Buttes? Earthcache EarthCache
Mesas or Buttes? Earthcache
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Difficulty:
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Terrain:
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Size: 
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As an earthcache, there is no “box” or “container” to discover. Rather, with this cache, you discover something about the geology of the area. For more info, consult www.earthcache.org
This is one in a possible series of I-40 Park-and-Earthcache caches that highlight various geological features in New Mexico. The parking pullout is just to the south of the Interstate ramps near the Continental Divide. There is plenty of space for Truckers/RVs to pull off and back on the ramps. It can be done from your car so is fully handicap accessible. There are now two earthcaches and a multi-cache available within minimum distances off this exit ramp so a THREE-FUR.
For paperless cachers, the logging requirements are at the beginning of the description.
Logging Requirements:
Send the answers to #1-#3 to me through my geocaching profile. DO NOT post the answers to any logging requirements on this site.
1.List the name “GC2J47C Mesas or Buttes? Earthcache” in the first line of your email. Also, list the number of people in your group.
2.As you look NORTH (over the Interstate) are the landforms that rise above the base MESAS or BUTTES? (see descriptions below).
3.Are there any evidences that CLIFF RETREAT has happened in the formations in front of you? If so, where A) straight north B) to the right (Northeast) C) to the left (Northwest) D) none visible from cords
4. (optional requirement based on GC.com guidelines, but it sure helps verify your smiley if your answers to the above are not “quite right”) Post a picture of yourself and/or your GPS with your log that shows you/GPS with either the “USA Rockets” or the “Continental Divide sign” in the background.
I will only respond if you have incomplete logging requirements. Go ahead and log your cache
Geology:
BUTTES and MESAS
are very similar rock landforms. BOTH have “caps” of erosion/weathering resistant rock (sandstone or limestone) and both “tower” above the surrounding plain. HOWEVER, there is a difference: Buttes are taller than they are wide, whereas MESAS are wider than they are tall. You are responsible for identifying the landforms in front of you as either BUTTES or MESAS.
CLIFF RETREAT:
Throughout the western part of New Mexico, the landforms are heavily influenced by erosion. In particular, water erosion. Different types of rocks are affected by erosion in different ways. Harder igneous rocks (like those created by volcanos) resist erosion, while softer sedimentary rocks are worn away by the same forces, but much more quickly. In this area, fairly resistant Sandstones and limestones often cap mesas, buttes, cuestas, and hogbacks protecting the mudstone and siltstone underneath, whereas in uncapped areas, the mudstone and siltstone are worn away easily by erosion and the less dramatic weathering forces of rain & snow (among others).
In cliff retreat, multiple layers of rock are exposed – in this case the base is a Triassic rock, the Chinle formation. It is very soft and easily eroded. Above this is the Jurassic Entrada Sandstone formation, which is much more resistant to erosion/weathering. These Jurassic era cliffs are a pleasing pink/red series of rocks/cliffs.
Because the Triassic era Chinle formation is soft, water and snow tend to wear it away, undermining the tall and resistant Jurassic era Entrada Sandstone. As the weight of these cliffs continue to gravitate, the red rocks break away from the cliff creating piles of super-sized rubble below and in front of the cliffs. Because of this event, the FACE of the sandstone cliffs “moves” away from the basin or plain where the softer rock is exposed (usually a river basin or plain). Your job is to decide if CLIFF RETREAT is happening here (see logging requirement).
Congrads to frankandjenny for FTF (First To Finish logging requirements) on 11-12-2010.
Resources:
Halka Chronic, Roadside Geology of New Mexico. Mountain Press Publishing. Missoula: Montana. 11th Printing, 2003.
Science Clarified. 2008. (visit link)
Additional Hints
(No hints available.)