CONFIRMED IMPACT CRATERS/STRUCTURES*

by: Charles O’Dale

*In my articles I use the term crater to define a circular impact depression and the term structure to define an impact crater that is severely altered by erosion.

  • CONFIRMED: an impact site with documented shock features and/or meteoritic material and/or observed fall.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Barringer, Arizona 1.19 0.049 ±0.003 Radioactive decay Simple1 Jointed
Beaverhead, Montana/Idaho ~100 ~600 K-Ar, 40Ar/39Ar and Rb-Sr Peak ring1 Allochthonous
Brent, Ontario 3.8 396 ± 20 K-Ar studies on the coarsely crystalline melt rocks Simple1 Overflight of Brent Crater
Calvin, Michigan 7.24 450 ± 10 Geological dating Complex1
Carswell, Alberta 39 115 ± 10 40Ar/39Ar Peak ring1 Multi-ring impact?
Charlevoix, Quebec 54 342 ± 15 K-Ar Peak ring1 Elevated Earthquake Zone
Chesapeake, Virginia 85 35.5 ± .3 Geological dating Complex1 Coesite in suevites
Chicxulub, Yucatan, Mexico 150 66.043 ±0.011 40Ar/39Ar Peak ring basin5 Cretaceous-Paleogene
Clearwater East, Quebec 26 ~460–470 Rb-Sr melt rocks Complex1 Chondrite-type
Clearwater West, Quebec 32 290 ± 20 K-Ar melt rocks Peak ring1  Maskelynite
Cloud Creek, Wyoming 7 ~190 ± 30 Geological dating Complex2 Chronostratigraphic
Crooked Creek, Missouri ~7 ~348 – 323 Geological dating Complex2 Serial impact event?
Decaturville Structure, Missouri 5.5 260-323 Geological dating CONFIRMED Complex2
Deep Bay, Saskatchewan 9.5 99 ± 4 Geological dating Simple Flat-floored1 Cretaceous sediments
Des Plaines, Illinois 8 <280 Geological dating Complex2
Eagle Butte, Alberta 10 <65 Geological dating Complex2 Shatter-coned Cretaceous rocks
Elbow, Alberta 8 395 ± 25 Geological dating Complex2 Brecciated Devonian strata
Flynn Creek, Tennessee ~3.8 382.03 ± 21 Geological dating Complex2 Shattercones
Glasford, Illinois ~4 443.8-485.4 Geological dating Complex2 Shattercones, shock metamorphism
Glover Bluff, Wisconsin 8 <500 Geological dating Complex2
Gow, Saskatchewan 5 <250 Radioactive decay Complex 2 Smallest currently known complex
Haviland, Kansas 0.01 0.02  ±0.002 Geological dating Simple1 Brenham meteorite
Holleford, Ontario 2.35 550 ±100 Geological dating Simple1 Overflight of Holleford Crater
Ile Rouleau, Quebec 4 <300 Geological dating Complex3 Age based on stratigraphy
Kentland, Indiana ~13 >97 Geological dating Complex1 Quarry
Lac Couture, Quebec 8 425 ± 25 Ar40-Ar39 melt rock Complex1 Submerged central peak
Lac La Moinerie, Quebec 8 400 ± 50 Ar40-Ar39 melt rock Complex1
Manicouagan, Quebec 100 214 ± 1 Zircon/melt rock dating Peak ring basin5 Maskelynite
Manson, Iowa ~35 73.8 Ar40-Ar39 melt rock Central peak1 No surface evidence
Maple Creek, Saskatchewan 6 <75 Geological & radioactive decay dating Complex5 Disrupts Late Cretaceous rocks
Middlesboro, Kentucky 6 <300 Geological dating Complex5 Dates to the formation of the supercontinent Pangaea 300 million years ago
Mistastin, Labrador 28 36.6 ± 2 Ar40-Ar39 melt rock Central peak basin6 Maskelynite
Montagnais, off Nova Scotia 45 50.5 ± 0.76 K-Ar, 40Ar/39Ar and Rb-Sr Complex1 Submerged south of Nova Scotia, Canada
Newporte, North Dakota 3.2 <500 Geological biostratigraphic dating Simple2 No surface evidence
Nicholson Lake, North West Territories 12.5 389 ± 6.7 Pb/U Complex1 The large island within the lake is the eroded central peak
Pilot Lake, North West Territories 6 445 ± 2 K-Ar, 40Ar/39Ar and Rb-Sr Complex2 Dating based on one sample
Pingualuit, Quebec 3.44 1.4 ± 0.1 Ar40-Ar39 melt rock Simple1 Overflight of Pingualuit Crater
Presqu’ile, Quebec 24 <500 Geological dating Complex1 High level erosion
Red Wing, North Dakota 9.1 200 ± 25 Geological dating Probable Complex8 Stratigraphy
Rock Elm, Wisconsin 6 420–440 Geological dating Complex7 Youngest exposed rocks
Slate Islands, Lake Superior 32 436 Ma ± 3 Ar40-Ar39 melt rock Complex1 Pseudotachylite dating
Steen River Albera 25 91 ± 7 K-Ar pyroclastic vesicular rock Complex1 Magnesioferrite MgFe2O
St. Martin, Manitoba ~40 227.8 ±0.9 Ar40-Ar39 melt rock Complex1 Maskelynite – Dauphin River diversion?
Sudbury, Ontario 250 1852 +4/-3 U-Pb zircon Multi ring?1 Sudbury Distal Ejecta
Upheaval Dome, Utah 5.5 <170 Geological dating Complex4 Younger than the Jurassic Navajo Sandstone
Viewfield, Saskatchewan 2.5 190 ± 20 Geological dating Simple2 Jurassic-Triasic post-impact deposit
Wanapitei, Ontario 3 to 7.5 37.2 ± 1.2 K/Ar, Ar40-Ar39 melt rock Simple – Possible flat-floored?1 Maskelynite – L or LL chondrite projectile
Wells Creek, Tennessee, USA ~12 200 ± 100 Geological dating CONFIRMED Complex Shattercones
West Hawk, Manitoba 2.44 100 Geological dating Simple1 No reliable age
Whitecourt, Alberta 0.036 0.00113 14C dating of charcoal Simple1 Medium octahedrite (Om) IIIAB

1 Dence, Michael R. Structural evidence from shock metamorphism in simple and complex impact craters: Linking observations to theory. Meteoritics & Planetary Science 39. Nr 2, 267-286 (2004).

2 Grieve R.A.F., Impact structures in Canada, Geological Association of Canada, 2006.

3 Spray J.G. et al. A marine magnetic study of the Ile Rouleau impact structure, Lake Mistassini, Quebec Canada. Meteoritics, 70th Annual Meeting (2007).

4 Eugene M. Shoemaker, Bryan J. Kriens, Ken E. Herkenhop, GEOLOGY OF THE UPHEAVAL DOME IMPACT STRUCTURE, SOUTHEAST UTAH. Journal of Geophysical Research–Planets, April 16, 1998.

5 Grieve R.A.F. and Head J.W. The Manicouagan impact structure: An analysis of its original dimensions and form. Journal of Geophysical Research 88:A807-A818 (1983).

6 French, B.M. Traces of Catastrophe, Lunar and Planetary Institute, 1998

7 Cordua, W. S., “The Rock Elm Structure, Pierce County, Wisconsin, a possible cryptoexplosion structure”, Geology, vol. 13, p. 372-374. 1985.

8Donofrio, Richard R., IMPACT CRATERS: IMPLICATIONS FOR BASEMENT HYDROCARBON PRODUCTION. Journal of Petroleum Geology, 3, 3, pp. 279-302, 1981.

“We, all of us, are what happens when a primordial mixture of hydrogen and helium evolves for so long that it begins to ask where it came from.”
Jill Tarter
CANADIAN CRATERS