Description: From Fierstein (2007): "One of the youngest preserved ash layers from Mageik, represented only by K-2198 in Mageik Creek, is also compositionally similar to the Y-flow, but is a few hundred years younger (∼2,500 14C years B.P.)."
"This section [the Mageik Creek section of Fierstein, 2007] has some regionally familiar players: the uppermost two pre-1912 tephras are the young grey ash (from Peulik?) and below it is a distinct yellow-tan very fine to fine ash layer correlated here with the mica-bearing ash (from Gas Rocks?). The lowermost pair of ash layers is correlated with two Mageik tephras (upper pale tan and lower grey ash layers). Between these pairs are two additional ash units. The lower of the two (sample K-2198) is an irregular 0.5- to 1-cm thick dark-grey fine crystal ash layer (plag+cpx+opx+mt; no ol). Glass shards (as seen by electron microprobe) tend to be very frothy with thin, stretched bubble walls. This has not been correlated with layers in other nearby sections, but lack of olivine precludes a source from Mount Griggs, the phenocryst assemblage and the glass and magnetite microprobe data are consistent with young East Mageik lavas, and it is sandwiched between young ash layers between ∼2,600 and 2,300 14C year B.P. Thus, this tephra is suspected to have been derived from Mount Mageik and, if so, is one of the youngest preserved ash layers from that edifice (favoring ∼2,500 14C year B.P.)."