“Elko Crater Field” Revisited
•Paper No. 239-14
•  "ELKO CRATER FIELD" REVISITED - RECONNAISSANCE REPORT
•  VERISH, Robert S., P.O. Box 237, Sunland, CA 91041, bolidechaser@yahoo.com.
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•  USGS Map Sheet MF-1168 by Ketner & Roddy (1980) is entitled "Map Showing the Elko Crater Field, Elko County,Nevada".
•  This poster reports on a subsequent field survey of this "Elko Crater Field". This survey was
•  conducted during Spring of 2001, and was intended to be only a reconnaissance effort for the purposes of securing evidence of ejecta or meteoritic
•  material, and to examine the stratigraphy of the craters. This survey did not result in any finds of ejecta or meteoritic material. A close inspection of the
•  stratigraphy of the "crater rims" did not reveal any evidence of disordered layering. All of the above is considered as negative evidence for an impact
•  origin for the Elko Crater Field. An exposure that is nearby a cluster of "craters" in the Susie Creek area revealed evidence, which affords an
•  interpretation for a terrestrial geologic origin for all of these depressions. A thin (~1m) veneer of colluvium overlies a section of volcaniclastic sediment
•  that can be divided into an upper and lower unit. The upper unit (~20m) is a light brown to tan-colored coarse sand that is interbedded with thinly
•  layered, fine-grained tuff. The lower unit is predominantly a greenish-gray bentonitic (expansive) clay. The base of the lower unit is not exposed in the
•  Susie Creek area, but where the tributaries come in contact with this unit, a flat-floored streambed is produced. The "craters" only occur within
•  exposures of this formation. In addition, many small landslides and soil slumps are in evidence throughout the Susie Creek area. The Elko Craters are
•  interpreted by this writer as being a subsidence feature within the "upper" volcaniclastic unit, the result of groundwater sapping of the "lower"
•  bentonite-rich unit. Typically, these depressions are rimmed by the uppermost "veneer" of cobble-rich colluvium which (in a process that is still not clear)
•  armors the rim against erosion, giving the appearance that the rim is "raised". Regardless of whether this interpretation is valid, the Elko Crater Field is a
•  unique and geologically striking feature that requires additional investigation. Should this interpretation have some merit, and given the ease these features
•  can be discerned in satellite imagery, there is the implication (if similar conditions can exist on Mars) that features originally interpreted as being craters
•  may actually be depressions produced through subsidence by groundwater sapping.
•  2002 Denver Annual Meeting (October 27-30, 2002)
•  Session No. 239--Booth# 104
•  Impact Stratigraphy (Posters)
•  Colo. Convention Center: Exhibit Hall