Mazama Ash

Mazama Ash
Stratigraphic range: Holocene
TypeMember[1]
Unit ofMount Mazama Formation[2]
Sub-unitsTsoyawata Bed, Mazama Bed[2]
Location
RegionNorthern North America
CountryUnited States, Canada, Greenland
Type section
Named forMount Mazama
Named byB.N. Moore, 1934.[3]

The Mazama Ash (formally named the Mazama Member in some areas)[1] 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 7640 ± 20[4] 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.[5]

Because it was deposited throughout a wide area at a known time, the Mazama Ash is an important marker bed for paleoclimatology, paleoecology, and archaeology, as well as for Quaternary geology and stratigraphic correlation.[6][7][8]

The ash particles and gasses from the Mazama eruption would have caused climate cooling for a period of several years after the eruption.[5] Throughout the northern Great Plains, the ash would have darkened the sky and a layer of ash at least several centimeters thick would have blanketed much of the landscape, causing severe disruptions for the native people and wildlife.[7][9]

  1. ^ a b National Geological Map Database. "Geologic Unit: Mazama". Retrieved 2 March 2020.
  2. ^ a b Jonathan Ogden Davis (1978), Quaternary tephrochronology of the Lake Lahontan area, Nevada and California, ASIN B0006WYF4O, Wikidata Q63856078
  3. ^ Moore, B.N. 1934. Deposits of possible Nuee ardente origin in the Crater Lake region, Oregon. Journal of Geology, vol. 42, p. 353-375.
  4. ^ Egan, Joanne; Staff, Richard; Blackford, Jeff (2015-03-25). "A high-precision age estimate of the Holocene Plinian eruption of Mount Mazama, Oregon, USA". The Holocene. 25 (7): 1054–1067. doi:10.1177/0959683615576230. ISSN 0959-6836.
  5. ^ a b Zdanowicz, C.M., Zielinski, G.A. and Germani, M.S. 1999. Mount Mazama eruption: Calendrical age verified and atmospheric impact assessed. Geology, vol. 27, no. 7, p. 621-624.
  6. ^ Spano, N.G., Lane, C.S., Francis, S.W. and Johnson, T.C. 2017. Discovery of Mount Mazama cryptotephra in Lake Superior (North America): Implications and potential applications. Geology, vol. 45, p. 1071-1074.
  7. ^ a b Oetelaar, G.A. and Beaudoin, A. 2005. Darkened skies and sparkling grasses: The potential impact of the Mazama ash fall on the northwestern Plains. Plains Anthropologist, vol. 50, no. 195, p. 285-305.
  8. ^ Cite error: The named reference White was invoked but never defined (see the help page).
  9. ^ Beaudoin, A. and Oetelaar, G.A. 2014. Investigating the environmental impacts and cultural responses to the Mazama ashfall on the northern Plains. Geological Society of America, Abstracts with Programs, vol. 46, no. 6, p. 460.