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Geologic Unit: Pearlette

Publication:
Cragin, F.W., 1896, Preliminary notice of three late Neocene 
   terranes of Kansas: Colorado College Studies, v. 6, p. 
   53-54.
Usage in Publication:
Pearlette ash

Modifications: Geologic Province: Dominant Lithology:
 Named
 Anadarko basin
 Las Vegas-Raton basin
 Cherokee basin
 Salina basin
 Ash

Summary:
Named as middle formation of the Tule division of Cummins (Equus beds of Cope); named for the old post office of Pearlette, Meade Co, KS, Anadarko basin. No type locality designated. Occurs west at least to Huerfano Park, CO, Las Vegas-Raton basin, and east to Sioux City, Dakota Co, NE, Salina basin, and Galena, Cherokee Co, KS, Cherokee basin. At several localities in KS, typically on Bluff creek, in Clark Co, occurs as middle succession of three terranes. Consists of a widespread horizon of white to brownish, rarely greenish, volcanic ash, 13 ft thick in a bed southwest of Meade Center. Thickness is considerably less in Clark and many other counties in KS, NE, etc, in which the ash has been found. Conformably overlies Meade gravels (new) and conformably underlies Kingsdown marls (new). Rarely contains fossils. Of late Pliocene age.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Hibbard, C.W., 1949, Pleistocene stratigraphy and paleontology 
   of Meade County, Kansas: Michigan University, Museum of 
   Paleontology Contributions, v. 7, no. 4, p. 63-90.
Usage in Publication:
Pearlette ash member

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Anadarko basin
 

Summary:
Removed from Meade formation (restricted) and reassigned as a member, in upper part, of Crooked Creek formation (new) in Meade Co, KS in the Anadarko basin. In a measured section in NE1/4 sec 20 and N1/2 sec 21, T33S, R28W, Pearlette is a 7+ ft thick gray impure ash that overlies unnamed brown silt, sand, and gravel that has the Cudahy fauna and underlies unnamed silt, clay, and sand with a Borchers fauna. Both unnamed units belong to the Crooked Creek. At type locality of the Meade formation, just west of Meade, KS along south side of U.S. Hwy 160, in some places Pearlette ash member rests directly on the Stump Arroyo member new), basal member of Crooked Creek. Unconformably underlies Kingsdown formation. Stratigraphic chart. Of Pleistocene age.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Hibbard, C.W., 1958, New stratigraphic names for early Pleistocene 
   deposits in southwestern Kansas: American Journal of Science, 
   v. 256, no. 1, p. 54-59.
Usage in Publication:
Pearlette volcanic ash

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Anadarko basin
 

Summary:
Assigned as an unranked unit to the Atwater member (new) of the Crooked Creek formation (revised) of the Meade group (revised). Is a 3.1 ft thick pearl gray, lenticular, impure ash that lies 15.5 ft above base of Atwater and 31.1 ft below top of Atwater. Of Pleistocene age. History of stratigraphic usage chart.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Semken, H.A., Jr., 1966, Stratigraphy and paleontology of the 
   McPherson Equus Beds (Sandahl local fauna), McPherson County, 
   Kansas: Michigan University, Museum of Paleontology Contributions, 
   v. 20, no. 6, p. 121-178.
Usage in Publication:
Pearlette Ash Member

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Sedgwick basin
 

Summary:
Lower unit of McPherson Formation of Williams and Lohman (1949), which contains Pearlette, reassigned to underlying Crooked Creek Formation of Meade Group in report area of northwest McPherson County, Kansas, Sedgwick basin. Age is early Pleistocene (late Kansan).
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Naeser, C.W., Izett, G.A., and Wilcox, R.E., 1973, Zircon 
   fission-track ages of Pearlette family ash beds in Meade 
   County, Kansas: Geological Society of America, Geology, v. 
   1, no. 2, p. 93-95.
Usage in Publication:
Pearlette family of ash beds*

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Anadarko basin
 Paradox basin
 

Summary:
Formerly thought to have been one ash-fall over the Great Plains and Rocky Mountain area. Recent petrographic and chemical studies of ash samples called Pearlette have shown that there are at least three different ash beds of closely related petrographic properties to tuffs in the Yellowstone area, WY. One, designated Pearlette type O [for occurrence at?] Onion Creek, SE1/4 NE1/4 sec 26, T24S, R24E, Grand Co, UT, Paradox basin has 0.7 +/-0.2 m.y. age, and occurrence at three localities in Meade Co, KS, Anadarko basin has 0.6 +/-0.07 to 0.9 +/-0.25 m.y. Type O correlates with Lava Creek Tuff of Yellowstone area. Pearlette type S (1.20 +/-0.04 m.y.) is correlated with Mesa Falls Tuff of Yellowstone area and is not well dated because zircons are of small size and paucity. Pearlette type B named for occurrence in Borchers local fauna at Cudahy mine, Meade Co, KS, Anadarko basin has an age of 2.0 m.y. and is correlated with the Huckleberry Ridge Tuff of Yellowstone area.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
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, 1 sheet, scale 1:4,000,000
Usage in Publication:
Pearlette family ash*

Modifications: Geologic Province: Dominant Lithology:
 Areal limits
 Many basins
 

Summary:
Term Pearlette ash widely used as a stratigraphic marker over the Great Plains for what was thought to be a single bed, and later divided into 3 ashes--type B, S, and O whose source area was the Yellowstone caldera complex. Type B recognized as the downwind equivalent of Huckleberry Ridge Tuff and called Huckleberry Ridge ash. Type S recognized as downwind equivalent of Mesa Falls Tuff called Mesa Falls ash. Type O recognized as the downwind equivalent of the Lava Creek Tuff called Lava Creek ash. Used as an informal name for ash for which chemical and mineralogical date not diagnostic to identify source tuff. Use as a formal member of Sappa Formation abandoned. Occurs in Las Vegas-Raton and Denver basins, CO; Great Basin province and Wasatch uplift, ID; Iowa shelf and Forest City basin, IA; Anadarko, Forest City, Salina, and Sedgwick basins, Central Kansas uplift, Nemaha anticline, Las Animas arch, KS; Gulf Coast basin, LA; Sioux uplift, SD; Palo Duro basin, TX; Nemaha anticline and Salina basin, NE. Inferred areal extent map.
Source: GNU records (USGS DDS-6; Denver GNULEX).