Ancient Dunes EarthCache
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This cache is located on the Red Rock Canyon Loop Drive within the Red Rock Canyon National Conservation Area. This is a fee area of the BLM, and costs $7.00 per vehicle. This fee is covered in the Golden Eagle Passport, Golden Age Passport, and Golden Access Passport. The Loop Drive opens at 6:00 a.m. every morning. Closure times are as follows: November 1 through February 28, 5:00 p.m.; March 1 through March 31, 7:00 p.m.; April 1 through September 30, 8:00 p.m.; and October 1 through October 31, 7:00 p.m. Please be aware that the desert tortoise is protected by law. If you are fortunate enough to see one, please view and photograph it from a distance.
At this cache, you will be looking at crossbeds of Aztec Sandstone. Aztec Sandstone is aeolian (windblown) in nature, and was laid down in the Jurassic Period, approximately 180 million years ago.
Aztec Sandstone: (main coordinates)
The coordinates will place you at the display plaque for the large Aztec Sandstone outcrop. This outcrop is the remnant of a once-immense field of sand dunes that stretched across much of the southwest. Over time, these dunes were buried, compacted, and turned to rock. Underground water moving through the dunes carried away much of the red color and left behind calcium carbonate.
Crossbeds: (N 36 08.898 W 115 25.840)
Take the trail north to the outcrop, then walk west along the trail to the coordinates listed above. At this location you will be at a small incised wash in the sandstone. Face the wall to the north.
Notice the alternating red and tan layers. These were formed while the dunes were still active. The inclined layers were formed when the winds blew the sand, and the sand stacked up on the windward side of the dune. Continued forward climbing movement of dune after dune resulted in the stacking of layer upon layer of cross bedded sands. After the sand turned to stone, the cross bed patterns remained.
Using a tape measure or ruler, measure off one foot perpendicular to the cross bedding. How many cross bedded layers did you find?
To log this cache:
1) Send me an email stating how many cross bedded layers you measured at this location.
Please consider posting photos of yourself, or the local geology, when you log this EarthCache. Photos can be an additional rewarding part of your journey, but posting them is not a requirement for logging this EarthCache, and is strictly optional.
The above information was compiled from the following sources:
Tingley, J.V. et al. Geologic Tours in the Las Vegas Area. Nevada Bureau of Mines and Geology Special Publication 16.
USGS. (visit link)
Geology of Red Rock Canyon. (visit link)
Red Rock Canyon. (visit link)
Additional Hints
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