Izett, G.A., and Wilcox, R.E., 1982, Map showing localities and inferred distributions of the Huckleberry Ridge, Mesa Falls, and Lava Creek ash beds (Pearlette family ash beds) of Pleistocene age in the western United States and southern Canada: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1325, scale 1:4,000,000
Use of Pearlette as a member of Sappa Formation abandoned. Type Sappa in the Salina basin, NE contains only Pearlette type O, or Mesa Falls ash bed, the informally designated downwind equivalent of the Mesa Falls Tuff of the Yellowstone caldera complex.
Source: GNU records (USGS DDS-6; Denver GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.
"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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).