- Usage in publication:
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- White Rock Mesa Member
- Modifications:
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- Original reference
- Dominant lithology:
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- Sandstone
- Shale
- AAPG geologic province:
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- San Juan basin
Owen, D.E., and Owen, D.E., Jr., 2005, The White Rock Mesa Member of the Dakota Sandstone (Cretaceous) of the San Juan basin, New Mexico and Colorado, a formal new lithostratigraphic unit to replace the informal "Dakota main body": New Mexico Geological Society Field Conference Guidebook, no. 56, p. 227-230.
Summary:
White Rock Mesa Member of Dakota Sandstone. Replaces informal "Dakota main body," above the K-3 unconformity in New Mexico and Colorado. Consists of, in order of abundance: (1) gray, tan-weathering, fine- to medium-grained, cross-bedded, quartz/chert sandstone that is locally pebbly, especially near the K-3 unconformity and at the base of channel-fills; (2) dark-gray to black, silty, carbonaceous shale; and (3) thin, lenticular coal beds with a high ash content. Average thickness approximately 30 m. At type underlies the X bentonite bed of Whitewater Arroyo Shale Tongue of Mancos Shale (Cretaceous); unconformably overlies Jurassic Salt Wash Sandstone Member of Morrison Formation (separated by K-3 unconformity). Age is early Late Cretaceous (Cenomanian).
Type section: measured at west end of White Rock Mesa, in NW/4 NW/4 sec. 36, T. 16 N., R. 17 W., approx. 14 km northeast of Gallup, Church Rock 7.5-min quadrangle, McKinley Co., NM. Named from White Rock Mesa. Extends into Colorado.
Source: Publication.
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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