Chalk Bluff EarthCache
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Difficulty:
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Size: 
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This cache is easily visible from the roadside. It is along West Fourth Street in West Reno near the Truckee River. Elevation 4661 ft.
"Chalk Bluff" is located in West Reno along the beautiful Truckee River. It is easily accessible by car by traveling through the older section of Reno's business district. The road cut is best viewed from across Fourth Street on the eastbound side of the roadway.
The chalk of Chalk Bluff is Tertiary-age siltstone and sandstone. Geologists refer to this as the Sandstone of the Hunter Creek. Its layers of white to cream-colored bedded rock are rich in diatomite. Diatomite has hundreds of industrial uses because of its high absorptive capacity. Its uses include filtration of water, beer, and sugar syrup. It is a mineral filler or extender in paper, plastics, paints, insecticides, and matches. It is also used as a mild abrasive in polishes. Diatomite can also be found in bricks and cement. The diatomite layers here are thin and impure and are of no commercial value, but provide an excellent example of how the once horizontal beds of sediments are now tilted to the east due to faulting. The apparent reddish-brown color, which is iron oxide, can be seen concentrated along the layers as well as the faults.
Above the road cut, evidence of the glacial-age ancestral river can be seen further up the cliff. The cliff is topped with a layer of gravel while the slope is covered with huge granite boulders. The occasional car-size granite boulders were also left by the glacial outwash, carried here and deposited by catastrophic floods from breaking ice dams up stream. These catastrophic glacial floods are called jökulhlaups, an Icelandic term for a flood caused by the sudden rapid draining of a glacier-dammed lake.
Question: After carefully collecting a diatomite sample, would you classify it as a soft or hard rock?
Information Sources:
Nevada Bureau of Mines and Geology
Tingley, J.V., Pizarro, K.A., Ross, C., Purkey, B.W., and Garside, L.J., 2005, Geologic and Natural History Tours in the Reno Area, Special Publication 19, Expanded Edition.
CAUTION:
Because this cache is located on a well-traveled roadside, please use extreme caution upon exiting your vehicle. Although it is a winding roadway, cars might be traveling at excessive speeds.
Additional Hints
(No hints available.)