Nanook Dome

About

Nanook Dome is a rounded mass of rock on the southeastern rim of Mount Edziza's summit crater in northwestern British Columbia, Canada. It has an elevation of 2,710 metres (8, 890 feet), slightly lower than the pinnacles on the southern crater rim which represent the highest points of Mount Edziza. The dome is about 750 m (2, 460 ft) in diameter, almost circular in structure and contains steep, smooth convex margins that reach heights of 150–200 m (490–660 ft). Its northeastern side is truncated by the headwall of an immense cirque containing Tenchen Glacier, but the current structure of the dome is nevertheless almost identical to its original form. Nanook Dome is one of three lava domes defined as part of the Edziza Formation, which is one of many geological formations comprising the Mount Edziza volcanic complex. The dome consists mainly of trachyte that erupted as viscous lava from a vent on the southwestern rim of Mount Edziza's summit crater. Some of the lava from this vent flowed into the crater where it ponded to form one or more lava lakes. Nanook Dome may have also been the source of some trachyte lava flows of the Kakiddi Formation, which exist in neighbouring valleys. Volcanism at the dome took place mainly during the Pleistocene, as did other domes of the Edziza Formation.

Adapted from Wikipedia (CC BY-SA). Photography via Wikimedia Commons.