page_title: Mazama Ash
section_title: Distribution
hierarchical_section_title: Mazama Ash / Distribution
caption_attribution_description: Cataclysmic eruption to present. Eruptions of ash and pumice: The cataclysmic eruption started from a vent on the northeast side of the volcano as a towering column of ash, with pyroclastic flows spreading to the northeast. Caldera collapse: As more magma was erupted, cracks opened up around the summit, which began to collapse. Fountains of pumice and ash surrounded the collapsing summit, and pyroclastic flows raced down all sides of the volcano. Steam explosions: When the dust had settled, the new caldera was 5 miles (8 km) in diameter and 1 mile (1.6 km) deep. Ground water interacted with hot deposits causing explosions of steam and ash. Today: In the first few hundred years after the cataclysmic eruption, renewed eruptions built Wizard Island, Merriam Cone, and the central platform. Water filled the new caldera to form the deepest lake in the United States. Figure modified from diagrams on back of 1988 USGS map “Crater Lake National Park and Vicinity, Oregon.”
context_page_description: The Mazama Ash is an extensive, geologically recent deposit of volcanic ash that is present throughout much of northern North America. The ash was ejected from Mount Mazama, a volcano in south-central Oregon, during its climactic eruption about 7600 years ago when Crater Lake was formed by caldera collapse. The ash spread primarily to the north and east due to the prevailing winds, and remnants of the ash have been identified as far northeast as the Greenland ice sheet.
  Because it was deposited throughout a wide area at a known time, the Mazama Ash is an important marker bed for paleoclimatology, paleoecology, and archeology, as well as for Quaternary geology and stratigraphic correlation.
  The ash particles and gasses from the Mazama eruption would have caused climate cooling for a period of several years after the eruption. Throughout the northern Great Plains, the ash would have darkened the sky and a layer of ash at least several centimetres thick would have blanketed much of the landscape, causing severe disruptions for the native people and wildlife.
context_section_description: The Mazama ash spread over an area of at least 900,000 km² (350,000 sq mi) in the northern Great Plains, where it is most commonly preserved within peat, alluvial, lacustrine, and aeolian sediments.  It is present in portions of the U.S. states of California, Oregon, Washington, Idaho, Montana, Nevada, Wyoming and Utah, as well as in the Greenland ice sheet, and in marine sediments off the coast of Oregon, Washington, and southernmost British Columbia.
  In Canada, deposits of Mazama Ash several centimeters thick are commonly present in southern areas of British Columbia, Alberta, and Saskatchewan. In southern Alberta, about 1,000 kilometres (620 mi) northeast of the eruption site, the Mazama Ash is typically found as a white band located several metres below the present ground surface. Shards of volcanic glass from the Mazama Ash have also been identified in the sediments of Lake Superior and in a bog in Newfoundland.
caption: Mount Mazama's eruption timeline, showing ejection of ash and caldera collapse.
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