CONFIRMED IMPACT CRATERS/STRUCTURES*

*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.

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
Carswell, Alberta 39 115 ± 10 40Ar/39Ar Peak ring1 Multi-ring impact?
Charlevoix, Quebec 54 342 ± 15 K-Ar Peak ring1 Elevated Earthquake Zone
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
Cloud Creek, Wyoming 7 ~190 +/- 30 Ma Geological dating Complex2 Chronostratigraphic
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
Glover Bluff, Wisconsin 8 <500 Geological dating Complex2
Gow, Saskatchewan 5 <250 Radioactive decay Complex 2 Smallest currently known complex
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
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 Radioactive decay Peak ring basin5 Zircon/melt rock dating
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
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
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
St. Martin, Manitoba ~40 227.8 ±0.9 Ar40-Ar39 melt rock Complex1 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 L or LL chondrite projectile
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