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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Willow Tank formation*
  • Modifications:
    • Named
  • Dominant lithology:
    • Conglomerate
  • AAPG geologic province:
    • Great Basin province
Publication:

Longwell, C.R., 1949, Structure of the northern Muddy Mountain area, Nevada: Geological Society of America Bulletin, v. 60, no. 5, p. 923-967.


Summary:

Named for exposures near Willow Tank about 5 mi southeast of Overton, Clark Co, NV in the Great Basin province. These exposures are designated the type section. Mapped (geologic map) as a unit unconformably above Aztec sandstone (Jurassic) and below the newly named Baseline sandstone (Upper Cretaceous). Ranges from 0 to 300+/-ft thick. Has a basal (0-30+/-ft thick) coarse conglomerate of well-rounded boulders as large as 10 to 12 inches [in diameter]. The overlying part of the formation consists of fine-grained deposits --buff to gray bentonitic clay and some layers of tuffaceous sandstone. Silicified wood, TEMPSKYA, UNIO; fossils listed. Assigned a Late Cretaceous age. Cross sections. Stratigraphic chart.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Willow Tank Formation*
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Plateau sedimentary province
Publication:

Bohannon, R.G., 1991, Geologic map of the Jacobs Well and southern part of the Elbow Canyon quadrangles, Mohave County, Arizona: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2167, 1 sheet, scale 1:24,000 [http://ngmdb.usgs.gov/Prodesc/proddesc_10162.htm]


Summary:

Extended from Muddy Mountains, Clark Co, NV into northwest Mohave Co, AZ, Plateau sedimentary province. Replaces Jacobs Ranch Formation. Unconformably overlies Navajo Sandstone; unconformably underlies lower conglomerate unit of Rainbow Gardens Member of Horse Spring Formation. Thickness is 60 m. Early Cretaceous age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates published by U.S. Geological Survey authors.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).

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