by: Charles O’Dale
Large Meteorite Impacts and Planetary Evolution II: The major portion of the data I quote in my documentation of impact structures was gleaned from this publication.
“I would rather have questions that can’t be answered than answers that can’t be questioned.” Richard Feynman
The scientific study of impact structures began only about 50 years ago. I’m dating myself, but that was about the time my interest in impact craters started. Like any kid, I spent hours looking at the craters on the Moon through my old telescope. Would I ever get a chance to explore a crater?Well since retirement, I have combined my hobbies of astronomy, geology and flying to explore impact craters and structures in North America from the air and ground.
You may think that the natural geological forces on our planet would have destroyed any features of impact craters. But, in some instances, these forces have “cross sectioned” the craters to ease our study. I have found the geology in these craters and structures fascinating!
While studying the physics of impact crater sites, I have found that circular geological features can also be produced by a number of geological processes.
Halliday I., and Griffin, A.A. 1964: Application of the scientific method to problems of crater recognition Meteoritics, vol. 2, No. 2.
These geological processes may include igneous activity (diatremes, maars, calderas, volcanoes, or syenite/plutons), dissolution and collapse of salt or carbonate rocks by groundwater (dolines), salt or shale diapirism, regional tectonism (circular fold-interference patterns or stratified circular features), glaciation (kettle holes), carbonate mounds, and by meteorite impacts (Stewart 2003).
Stewart S. A. 2003: How will we recognize buried impact craters in terrestrial sedimentary basins? Geology 31:929–932.
My science background plus the experience that I have gleaned from my past profession of semiconductor failure analysis has given me the incentive to document my analysis of these craters and structures. I encourage anyone to please contact me if they note any errors that I may have made in my documentation or if they have something to add.(A few of my expeditions actually resulted from suggestions made from readers of this site).
Many of the other exploration trips that I have made in GOZooM and on foot can be viewed here and here.
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“How bright and beautiful a comet is as it flies past our planet – provided it does fly past it” ISAAC ASIMOV “All things originate from one another and vanish into another … according to time” ~ANAXIMANDER
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“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
“Civilization exists by geological consent …. subject to change without notice.”
– W. Durant –
CRATER URL References
For the complete physics of impact crater formation I recommend the following references:
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- VIDEO – CRATER EXPLORATIONS
- Air&Space SMITHSONIAN
- United States Meteorite Impact Craters
- Ernstson Claudin Impact Structures – Meteorite Craters
- Meteor/Meteorite News
- A CATASTROPHE OF COMETS
- The recognition of terrestrial impact structures,
- Large Meteorite Impacts and Planetary Evolution II,
- Traces of Catastrophe,
- Why Does The Moon Have Craters?
- B612 Foundation
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Data Updates
UPDATE ARCHIVES
5. RASC 150
Components of the RASC Sesquicentennial Logo:
The aurora borealis is a quintessentially Canadian space-weather phenomenon, one shared with other high latitude cultures. RASC members have contributed to the scientific, historical, and artistic investigation of the northern lights, and have promoted their recreational enjoyment.
The Manicouagan astrobleme (214 ± 1 Ma) represents the major discovery of sites of impact cratering in the Canadian Shield, an effort pioneered by astrophysicists and geophysicists at the Dominion Observatory (ca. 1950-), many of whom were RASC members. This world-impacting research played a crucial role in changing scientific and popular perceptions of crater-forming mechanisms, solar-system history, and planetary geology. The representation of the crater also acknowledges Canadian excellence in meteor dynamics, meteorite petrology, meteorite curation, and the RASC’s long-standing interest in such work.
The stars represent the major Canadian contributions to stellar spectroscopy done at the Dominion Observatory, the Dominion Astrophysical Observatory (also see this), the David Dunlap Observatory,(additionally refer to this) and elsewhere (ca. 1905-), whose major contributors were also RASC members (such as J.S. Plaskett [1865-1941], the first Canadian astrophysicist of international repute). The stars also symbolize the asteroseismology, exoplanet transits and eclipses, and investigations into stellar variability through precise photometry achieved by the Microvariability and Oscillations of STars space telescope(MOST, 2003-).
The globular cluster recognizes the field of Helen Sawyer Hogg‘s (1905-1993) greatest scientific contributions (ca. 1926-ca. 1993), and the Helen Sawyer Hogg Telescope (HSHT) at the University of Toronto Southern Observatory at Cerro Las Campanas, one of Canada’s first ventures (1971-1997) in exploring off-shore astronomical installations, which has born lasting fruit in international cooperative installations exploring the full range of astrophysical phenomena, such as the Canada-France-Hawaii Telescope (CFHT, 1979-), the James Clerk Maxwell Telescope (JCMT, 1986-2015 [period of direct Canadian involvement & funding]), the Gemini Telescopes (North 1999-, South 2000-), the Atacama Large Millimetre Array (ALMA, 2011/2013-), the Square Kilometre Array (SKA, 2020-), and the Thirty Metre Telescope (TMT, ca. 2022-).
The spiral galaxy represents both the work of Canadian observational cosmologists (e.g., Sidney van den Bergh‘s classification of Galaxy morphology, Laura Ferrarese‘s work on the morphology & dynamics of early type galaxies), as well as the efforts of amateur Canadian observers of deep-sky objects (DSOs), and imagers.
The comet stands for the contributions to cometography by Canadian comet discoverers, such as David Levy, Rolf Meier, and Chris Wilson.
The Moon symbolizes an object important for first nations’ calendrics, and the earliest recorded observations by Europeans in Canada (17th century lunar reports, and lunar eclipse reports). The Moon together with the stars symbolizes the practice of navigational astronomy on land and water, which was crucial to the formation of Canada. Finally, the Moon is as popular an object for RASC members to share with the public when doing outreach as it was 150 years ago.
R.A. Rosenfeld
CRATERS SORTED BY;
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- Alphabetically listed;
- Confirmed; an impact site with documented shock features and/or meteoritic material and/or observed fall.
- Probable; structural, geological and geophysical studies established reasonable evidence, possibly with unconfirmed reports of shock features in abstracts, but the definite shock features and/or meteoritic material is not well documented.
- Proposed; some structural, geological and/or geophysical evidence exists but the impact origin is still highly uncertain for the lack of data.
- Improbable; observations of the structure and/or geological context suggest a non-impact origin but alternative interpretation has not been well established.
- Non-Impact; a non-impact origin has been well documented.
- Extinction;
- REFERENCES1 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, 19987 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