Geology and Minerals

Edziza Formation

The Edziza Formation ( əd-ZY-zə) is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada. First described in 1984, the Edziza Formation was mapped as one of several geological formations of the Mount Edziza volcanic complex. It overlies at least four other geological formations of this volcanic complex that differ in age and composition. The main volcanic rock comprising the Edziza Formation is trachyte which was deposited by volcanic eruptions at the end of the third magmatic cycle of the Mount Edziza volcanic complex 0.9 million years ago. Trachyte of the Edziza Formation is in the form of lava flows and pyroclastic rocks that comprise the central stratovolcano of Mount Edziza, as well as lava domes on its summit and flanks. At least four lava lakes ponded inside the summit crater which cooled into four rock units that are exposed in the breached eastern crater rim. These lava lakes overlie rock fragments inside the central volcanic conduit which accompanied with collapse of a narrower and higher summit.

Also on this shelf

See also

• ▸Direct air capture
• ▸Basel drum
• ▸Farallon Islands

Uncatalogued shelf

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