Description

From Wood and Kienle (1990) ^[1] : "The Togiak volcanics are a late Pleistocene set of thin (<20 m thick) lava flows underlying ~450 square km of the Togiak River valley in southwest Alaska. The flows are largely covered by glacial deposits, but excellent exposures occur in sea cliffs on Togiak Bay and along cutbanks of various rivers. Three probable vents have been detected; the most interesting is a 300-m-high tuya or subglacial volcano. Togiak Tuya is 6 km long x 2.5 km wide and is elongated parallel to regional faults and the flow of glacial ice. The elongated shape suggests formation in an actively flowing glacier; most other tuyas apparently formed in stagnant ice. Sideromelane tuff and pillow basalts make up the main mass of the tuya, but the top 40-50 m are subaerial flows, formed where the volcano grew above the glacier. It has been speculated that the tuya may have formed during a glacial period ~39,000 yr ago, and a single K-Ar age of 0.76 Ma is recorded for the underlying basalts, all of which have normal magnetic polarity. The lavas are confined to a graben between northeast-trending faults, and appear to have erupted from vents along the faults."