Description: From Fierstein (2007): "The oldest flows from East Mageik (unit "meo" of Hildreth and Fierstein 2003) have more degraded surfaces than their younger counterparts, although they are not obviously ice-scoured...Tephra deposits possibly associated with this eruptive episode are three older ash layers identified in the Angle Creek key section: the bluish-grey ash (just below K-2500G: ∼6,000-6,700 14C years B.P.), the thick gritty salmon ash (K-2500E: underlying peat is 8430+/-115 14C years B.P.) and the thick orange-tan ash (K-2500B: ∼9,260 14C years B.P.). Glass shards from the thick gritty salmon ash span a wider SiO2 range (74-78 wt.%) than those from the bluish-grey and the thick orange-tan (74-76 wt.%) ashes, while oxide data for all three ash layers overlap (Fig. 23 [in original text]). Microprobe data for these ash layers are so similar to those from younger East Mageik tephra that I am fairly confident they, too, are from East Mageik. The total eruptive volume of the East Mageik lavas is 5-6 km3, to which the dacitic falls and one small andesitic pyroclastic-flow deposit preserved locally atop "meo" add no more than 0.1 km3 (Hildreth and Fierstein 2000). Thus, over a period of ∼7,000 years, the preserved tephra record suggests there may have been at least six eruptive episodes from East Mageik plus one phreatic event, each separated by as little as 100 years to as much as 2,700 years."
"Only 1 to 3 cm below the lower ash rib [at the Angle Creek section] is a laterally discontinuous but commonly preserved light grey fine ash. Although thin here (1-3 mm) and not collected, this layer is tentatively correlated with a bluish-grey fine ash found widely in the Windy Creek drainage (4 cm thick; Fig. 3 [in original text]), on the east side of the lower VTTS (3 cm thick, K-2590), and nearby in Willow Creek (3.5 cm thick, K- 2588; Fig. 2 [in original text]). Stratigraphic position strongly suggests this ash is also found in Margot Creek (1 cm thick), in Martin Creek (3 cm thick, K-2339A; Fig. 2 [in original text]), is the basal ash in a section near the east margin of the VTTS at the foot of Mt. Griggs (4 to 7 cm thick, K-2345), and is a normally graded 4-cm fall in upper Angle Creek, K-2072). Microprobe data for three of these samples (lower VTTS and Martin Creek) shows they not only correlate well with one another, but also with other tephras from Mount Mageik (younger ones: lower grey and ODLF, and older ones: thick gritty salmon, and thick orange-tan; Figs. 3, 13 [in original text]). Thickness, grain size, stratigraphy, and limited microprobe data are all consistent with this ash originating from East Mageik, with a northerly to NNE dispersal. Radiocarbon dates on loess and organic-richer soils beneath the tephra yield 5,800+/-50 (head of Angle Creek, K-2072), 6,420+/-240 (Windy Creek, K-2544), 5,670+/-170 (Margot Creek, K-2513G), and 6,720+/-140 14C years B.P. (see Table 2 [in original text])."