Shaken not Stirred EarthCache
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This earthcache is located between Jackpot, NV and Contact, NV approximately 8 miles south of Jackpot on a short section of old US 93 running approximately parallel to the existing U.S. 93. Going south from Jackpot it angles off to the right.The co-oridinates of old US 93 & US 93 is N41 51.567 W114 42.773. Going north from Contact take the Mahogony Basin road and turn north at the first road. Good road for any type vehicle. and is in good condition
"Shaken not Stirred", The famous quote from the James Bond movies can be applied to understanding the volcanic ash deposits located between Jackpot and Contact in Northern Elko County, Nevada. Layers of ash and lava flows in this wide open area suggest that a lake of unknown size occupied this basin, perhaps more than once.
A few of the roads in the area cut thru the bedded (layered) but fairly loose horizontal or cross-bedded layers of ash. In this roadcut the layers are now masses of swirls and peaks surrounding oval bulbs of sediment. Something shook these layers vigorously enough to cause some of the layers to liquefy and flow upward around other layers that were sinking. To get some understanding of what happened if you fill the bottom half of a large clear bowl with white cake batter then carefully pour chocolate batter on top so you have two horizontal layers of two colors of cake batter. Shake the bowl. With the proper amount of shaking the layers will begin to mix in a chaotic fashion, creating swirls and peaks. This is called 'liquefaction', and is most often seen along coastlines subjected to earthquakes. It can often be used to date the seismic event.
If the lakebed deposits were compacted just right and the amount of water within the sediment was adequate, shaking produced by an earthquake would have liquefied that part of the lakebed, causing it to flow and settle. When this happened, some of the soil flowed upward around the soil above it creating the appearance of swirls and peaks.
Notice how the lowest chaotic layer moved upward around the layers above creating bulbs of sediment surrounded by peaks and swirls. Also notice how this layer rests on top of the originally horizontal material still in place below.
In the roadcut to the north are signs of a possible faultline that may have been responsible for the shaking that produced the chaotic beds. of On the east side of the cut you will notice a light brown vertical deposit cutting thru the more horizontal beds of ash. It looks like debris that slid down from the surface. This may have been an old fault fracture now filled with small pebbles and fine altered ash.
I would like to thank Lawrence P. Growney, Geologist for providing the information on this site in Northern Nevada.
LOGGING REQUIREMENTS
email the answers to the following questions to sacypher@earthlink.net
1. The approximate width of the light brown vertical deposit (faultline) that cuts thru the horizontal (level) layers in the northern roadcut. (not the width of the roadcut)
2. Do you see any other signs of earthquake activity if so what?
3. The number of people in your party, and a picture of you and your gps by the swirls and peaks.
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