Source Area of Great Plains Pleistocene Volcanic Ash

The Bishop Ash Bed, a Pleistocene Marker Bed in the Western United States

“…The petrographic and chemical characteristics of the Pearlette-like ashes have strong family resemblances to Pleistocene air-fall rhyolitic ash from eruptive centers in the Yellowstone Xational Park area of Wryoming and Idaho, and we suspect that these eruptive centers are the sources of the Pearlette-like ashes. The Pearlette-like ashes differ significantly in mineralogic and chemical composition from Pleistocene nirfall rhyolitic ash of the Jemez Mountain eruptive centers in Sew Mexico, previously suggested as a "Pearlette ash" source (Swineford. 1949).…”

Regional interpretation of Kansas aeromagnetic data

“…The deposits are located primarily in the northwestern part of the state (Carey,et al, 1952). Essentially all of the volcanic ash layers occurring in Pleistocene sediments were deposited within one stratigraphic member, but are distributed throughout much of Kansas as shown by Figure 8 -6. The source of the Pleistocene ash in Kansas has been attributed to volcanoes in north-central New Mexico (Swineford, 1949) and in the Yellowstone Park area of Wyoming and Idaho (Boellstorff, 1976).…”

Geomorphological Processes on Terrestrial Planetary Surfaces

“…Layers of tephra incorporated within other Quaternary materials have long been used as a basis for correlation and relative www.annualreviews.org/aronline Annual Reviews dating (Swinford 1949, Wilcox 1965, D. G. W. Smith & Westgate 1969, Izett et al 1970, H. W. Smith et al 1977a, b, Porter 1978. Modern chemical and petrological analyses provide means of fingerprinting tephra layers from different sources more effectively (Borchardt et al 1971), and improvements in precision of 4°K/4°A analyses of younger materials have made absolute age assignments increasingly reliable.…”