Espenberg reported activity

Event Name : Espenberg North Killeak Maar

Stop: 40000

Years BP Tephrochronology

Maar, tuff cone, tuff ring:

Description: From Hopkins (1988): "The youngest and most spectacular volcanic features in the Devil Mountain-Cape Espenberg area consist of a group of five maars (shallow, broad, low-rimmed explosion craters formed by eruptions rich in steam)."

"The original basin of North Killeak is nearly circular and has a diameter of 3.2 kilometers. Two short, faint swales are the only traces of base-surge rings to be seen around the perimeter of the North Killeak Lake maar (Figure 7-3c [in original text]). The lake shore is separated in most places from relatively gentle basin slopes by a belt of ice-rampart ridges ranging from 120 to more than 500 meters wide. The ice rampart ridges are readily distinguished from concentric rings ascribed to base surges. Concentric rings ascribed to base surges lie entirely outside the original crater walls and are generally much wider and have much more relief than do the ice rampart ridges steep slopes along the south shore expose ledges of welded tuff-breccia and compact black, pisolitic accretionary lapilli (clear indications of wet tephra; J.Kienle, written communication 8/87). Loess is exposed in frost-scars at the crest of the slope."

From Beget and others (1996): "...South Killeak Maar is >40,000 years old; North Killeak Maar is somewhat older..."