Red Rock Canyon is a great place to visit with your family. The scenery is amazing and there are lots of great hikes available.
Layers of Colour
The vivid colours of the various rock layers make for an impressive sight. The grey rock is composed of limestone and dolostone and is much older than the red or tan sandstone that you see. Millions of years ago, most of this area was covered by ocean and the limestone accumulated from dead marine plants and animals which deposited in layers up to 9,000 feet thick and solidified over time.
While the limestone was created in the ocean, the sandstone came from desert sand dunes. During the Jurassic period, much of the southwestern United States was covered in desert. The sand dunes were up to a half mile thick and they were hardened due to a process called lithification which involves the sand being cemented with calcium carbonate and sometimes also iron oxide.
Why is it red?
The red colour is caused by the presence of iron. When iron is exposed to rain and air it oxidizes and turns red, brown or orange in colour. In the tan sandstone, there is an absence of iron either because water leached it out or iron was never deposited there. You will also see red spots in the sandstone which are due to iron concretions. This happens when water below the surface precipitates iron oxide around a nucleus in the sandstone. These erode less easily than normal sandstone and can turn into little balls called Moqui Marbles.
To log this Earthcache, e-mail answers to the following questions to the cache owner.
Question 1: The posted coordinates for this earthcache take you to a sign near the parking lot.
- How old is the grey limestone/dolostone?
- How old is the red and tan sandstone?
- Are these rocks igneous, sedimentary or metamorphic?
Question 2: Approximately when did a vast series of thrust faults develop that built mountains throughout western North America?
Question 3. Optional - feel free to post a picture of you or your GPSr near the posted coordinates. Please do not include a picture of the interpretive signs though.
Logs will be deleted if an e-mail containing the correct answers isn't received within 1 week. Also, please be respectful of the area when you are visiting. Thanks!! I hope you will enjoy your visit to Grotto Canyon and also learn something in the process!
Acknowledgements:
Thanks goes out to the Outdoor Recreation Planner for the Red Rock Sloan Field Office, Southern Nevada District for approving this earth cache!
References:
"Red Rock Canyon Interpretive Association | Las Vegas, Nevada." Red Rock Canyon Interpretive Association | Las Vegas, Nevada. N.p., n.d. Web. 30 Oct. 2016.
"Canyon." National Geographic Society. 20 May 2011. Web. 31 Oct. 2016.
"Red Rock Canyon National Conservation Area." Wikipedia. Wikimedia Foundation, n.d. Web. 01 Nov. 2016.
Fensome, Robert A., G. L. Williams, Aicha Achab, J. J. Clague, David Corrigan, J. W. H. Monger, and Godfrey S. Nowlan. Four Billion Years and Counting: Canada's Geological Heritage. Toronto: Canadian Federation of Earth Sciences and Nimbus, 2014. Print.
