Subglacial mound

A subglacial mound (SUGM) is a rounded subglacial volcano. These kinds of volcanoes form when lava erupts beneath a thick glacier or ice sheet.cite web | title = Types of volcanoes | work = Volcanoes of Canada | publisher = Geological Survey of Canada | date = 2008-02-25 | url = http://gsc.nrcan.gc.ca/volcanoes/type_e.php | accessdate = 2008-09-24] The magma forming these volcanoes were not hot enough to melt a vertical pipe right through the overlying glacial ice, instead forming rounded conical mounds of hydrated volcanic fragments called hyaloclastite and lava that solidified into pillow-shaped masses called pillow lava deep beneath the glacial ice field. Once the glaciers had retreated, the subglacial volcano would be revealed, with a unique shape as a result of their confinement within glacial ice. They are somewhat rare worldwide, being confined to regions which were formerly covered by continental ice sheets and also had active volcanism during the same period. They are found throughout Iceland, British Columbia, and Antarctica.

Subglacial mounds can be mistaken for cinder cones because they may have a similar shape.cite web | title = Pyramid Mountain | work = Catalogue of Canadian volcanoes | publisher = Geological Survey of Canada | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=wcb_pmt_023 | accessdate = 2008-09-24] An example of this confusion is Pyramid Mountain in the Wells Gray-Clearwater volcanic field of east-central British Columbia, Canada.

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