Petersburg 22 mi (36 km) NE Point Baker 22 mi (36 km) SW Kupreanof 22 mi (36 km) NE Port Protection 23 mi (37 km) SW Anchorage 680 mi (1094 km) NW
From Wood and Kienle (1990): "Olivine-bearing tholeiitic basalt with average K-content, together with minor sodic alkalic basalts, overlie volcanic-rich gravel and glacial till along the southern coast of Kupreanof Island west of Duncan Canal. The flows are recognized in the field by their conspicuous fresh-appearing pahoehoe and aa surfaces. Two probable vents lie within the Mesozoic and Paleozoic rocks of the Duncan Canal fault zone north of the main exposures; the northern one contains scattered peridotite nodules. The relations of the main exposures to the subjacent middle Tertiary volcanic rocks of the Kuiu-Etolin volcanicplutonic belt are not clear at the western end of the field because the Holocene basalt is difficult to differentiate from the adjacent older basalt."