AGE vs EPOCH

CRATER IMPACT AGE vs EPOCH

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.

Also see:  EXTINCTIONS VS Possible Impact Relationship

ARCHEAN: 4.6 BILLION –2.5 BILLION

HADEAN: 4.6 BILLION -3.8 BILLION

  • Formation of the Earth;
  • A huge planetoid crushes into Earth & splits off Moon;
  • Massive meteor bombardments pound Earth and Moon;
  • Interior of the molten Earth separates into layers;
  • Dense, very hot atmosphere of hydrogen, CO², steam, ammonia & methane – no oxygen;
  • Boiling steam begins to condense into oceans;
  • Earliest known rocks on Earth date from the Hadean;
  • Organic chemical components of the building blocks;
    of life (amino acids, RNA and DNA) first appear.

ARCHEAN: 3.8 BILLION -2.5 BILLION

  • The Earth’s temperature 3 times hotter than today;
  • The Earth’s crust very thin;
  • Enormous volcanic and tectonic activity;
  • Protocontinents begin to form over hotspots;
  • Dense, hot atmosphere of CO², methane and ammonia;
  • Oceans hot, acidic and filled with dissolved metals;
  • First life appears as simple prokaryote bacteria;
  • Single-celled archaea extemophiles appear;
  • Cyanobacteria appear & begin forming stromatolites;
  • Cyanobacteria develop photosynthesis & begin pumping oxygen into the atmosphere.
Rodinia formed at c. 1.23 Ga by accretion and collision of fragments produced by breakup of an older supercontinent, and assembled by global-scale 2.1–1.82 Ga collisional events. Orogenic belts of 1.1 Ga age are highlighted in green.

Orogeny is an event that leads to a large structural deformation of the Earth’s lithosphere (crust and uppermost mantle) due to the interaction between tectonic plates.

  •  Earth was still about three times as hot as it is today;
  • Most of the Earth was covered with oceans;
  • Earth’s atmosphere was mainly carbon dioxide;
  • low oxygen levels;
  • Few small cratons formed by volcanoes;
  • Most of the rocks were igneous or metamorphic like granite or quartz;
  • Earliest sedimentary rocks like sandstone also formed in the oceans;
  • Earliest living cells formed in the oceans, evolved into simple prokaryote cells;
  • By three billion years ago, prokaryote cells evolved photosynthesis;
  • excreted (pooped out) oxygen;
  • Iron and sulfur rocks mixed with early oxygen atoms to make rusty red rocks and limestone;
  • Many large asteroids that hit the Earth during the Archaean Eon. 
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Hudson Bay Arc >450  <4,600  Arc rock age IMPROBABLE Multi ring basin? No impact metamorphism found

PROTEROZOIC: 2.5 BILLION – 542 MILLION

600 million years ago, a supercontinent known as Rodina split apart, and a vast ocean filled the basin. Map courtesy of CR Scotese, PALEOMAP Project
  • multicellular organisms appear;
  • 2.45–1.85 Ga: O2 produced, but absorbed in oceans and seabed rock;
  • 1.85–0.85 Ga: O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer;
  • Rodinia Supercontinent comes together[
  • All oceans merged into one – Mirovia;
  • Considerable mountain building;
  • Ocean and atmosphere reach chemical composition approximately same as today;
  • All land is barren, lifeless desert.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Sudbury, Ontario 250 1852 +4/-3 U-Pb zircon CONFIRMED Multi-ring? Sudbury Distal Ejecta
Skeleton Lake, Ontario 3.5 ~800 Geological dating PROBABLE Simple
Beaverhead, Montana/Idaho ~100 ~600 K-Ar, 40Ar/39Ar and Rb-Sr CONFIRMED Peak ring Allochthonous
Holleford, Ontario 2.35 550 ±100 Geological dating CONFIRMED Simple Overflight of Holleford Crater

CAMBRIAN: 542 – 488 MILLION

500 million years ago a chunk of the supercontinent Pannotia drifted north and split into three masses, forming Laurentia (present-day North America), Baltica (present-day northern Europe), and Siberia. In shallow waters, the first multicellular animals with exoskeletons appeared, and an explosion of life began. Map courtesy of CR Scotese, PALEOMAP Project
  • multicellular organisms gradually became more common, produced the first representatives of all modern animal phyla;
  • mean surface temperature 7 °C above modern level;
  • sea level 30m above present day, rising steadily to 90m;
  • Pannotia splits up into masses that will become Laurentia and Gondwana;
  • Panthalassic Ocean forms with wide shallow seas;
  • Climate very warm with high oxygen content;
  • All land is barren, lifeless desert;
  • First vertebrates appear;
  • Many strange “experimental” forms appear, but many
    die out in mass extinction at the end of the period.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Touchwood Hills, Saskatchewan >200 >541 Post Williston Basin deposit IMPROBABLE Multi-ring Basin?
Glover Bluff, Wisconsin 8 <500 Geological dating CONFIRMED Complex
Can-Am, Lake Huron 100 ~500 Geological dating PROBABLE Complex Underwater in Lake Huron
Presqu’ile, Quebec 24 <500 Geological dating CONFIRMED Complex High level erosion
Newporte, North Dakota 3.2 <500 Geological biostratigraphic dating CONFIRMED Simple No surface evidence

ORDOVICIAN: 488 – 443 MILLION

  • Cambrian–Ordovician extinction event,
  • diversity of life increases, fish are the first true vertebrates;
  • O2 68 % of modern level;
  • mean surface temperature 2 °C above modern level;
  • sea level 180m above present day, rising to 220 m and falling sharply to 140 m in end-Ordovician glaciation;
  • 100 times as many meteorites struck the Earth per year during the Ordovician compared with today;
  • Appalachians first formed, Laurentia and Gondwana hover near equator, wide shallow seas; climate warm but later cools;
  • First life on land – primitive liverwort plants and fungi;
  • The period ends in ice age and extinction.
Researchers have discovered minerals from 43 meteorites that landed on Earth 470 million years ago. More than half of the mineral grains are from meteorites completely unknown or very rare in today’s meteorite flow. These findings mean that we will probably need to revise our current understanding of the history and development of the solar system. Credit: Image courtesy of Lund University
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
James River, Alberta 4.8 <480 Geological dating PROBABLE Complex No surface expression
Clearwater East, Quebec 26 ~460–470 Rb-Sr melt rocks CONFIRMED Complex Chondrite-type
Calvin, Michigan 7.24 450 ± 10 Geological dating CONFIRMED Complex
Pilot Lake, North West Territories 6 445 ± 2 K-Ar, 40Ar/39Ar and Rb-Sr CONFIRMED Complex Dating based on one sample
Bear Swamp, New York 3.5 ~444 Geological dating PROBABLE Simple No surface expression

SILURIAN: 443 – 416 MILLION

  • Ordovician–Silurian extinction event 60% of marine genera wiped out;
  • O2 70 % of modern level;
  • mean surface temperature 3 °C above modern level;
  • sea level 180m above present day with short-term negative excursions (glacial cause);
  • Euramerica forms as Gondwana drifts north
  • Wide shallow seas as Ordovician glaciers melt
  • Warm, greenhouse climate
  • Most land is barren, lifeless desert
  • Life begins to creep onto land – primitive plants, ferns
    fungi and myriapoda lead the way, the age of Arthropods.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Slate Islands, Lake Superior 32 436 Ma ± 3 Ar40-Ar39 melt rock CONFIRMED Complex Pseudotachylite dating
High Rock Lake, Manitoba ~5 435 ± 10 Geological dating PROBABLE Complex
Lac Couture, Quebec 8 425 ± 25 Ar40-Ar39 melt rock CONFIRMED Complex Submerged central peak
Rock Elm, Wisconsin 6 420–440 Geological dating CONFIRMED Complex Youngest exposed rocks

DEVONIAN: 416 – 359.2 MILLION

  • O2 75 % of modern level;
  • mean surface temperature 6 °C above modern level;
  • sea level 180m above present day gradually falling to 120m;
  • Euramerica and Gondwana drift towards each other;
  • The Age of Fishes and the Invasion of Land;
  • Ocean levels high with wide shallow seas;
  • Warm, greenhouse climate;
  •  Late Devonian extinction  – all placodermi (armoured prehistoric fish), and trilobites die off.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Franktown structure, Ontario ~2 >400 Ordovician sediment cover PROPOSED Simple Circular depression
Lac La Moinerie, Quebec 8 400 ± 50 Ar40-Ar39 melt rock CONFIRMED Complex
Brent, Ontario 3.8 396 ± 20 K-Ar studies on the coarsely crystalline melt rocks CONFIRMED Simple Overflight of Brent Crater
Elbow, Alberta 8 395 ± 25 Geological dating CONFIRMED Complex Brecciated Devonian strata
Nicholson Lake, North West Territories 12.5 389 ± 6.7 Pb/U CONFIRMED Complex The large island within the lake is the eroded central peak
Flynn Creek, Tennessee ~3.8 382.03 ± 21 Geological dating Complex2 Shattercones
Panther Mountain, New York state 10 ~375 Geological dating PROBABLE Complex Inverted relief

MISSISSIPPIAN: 359.2 – 318 MILLION

    • Epoch opens in slow mass extinction, life soon recovers, the age of  amphibians;
    • Euramerica & Gondwana continue to merge; much mountain building; other continent fragments drift closer;
    • Vast forests and swamps form as sea levels fluctuate;
    • Climate hot & humid but glaciated at the poles
    • Oxygen level 40% above today – abundant wildfires
    • amphibious tetrapods multiply wildly; many grow enormous in the high humidity and oxygen;
    • Sea life dominated by sharks, corals, bryozoa,brachiopods, ammonoids, crinoids and foraminifera;
    • much of the world’s coal formed in the Carboniferous
    • Carboniferous Period lasted from about 359.2 to 299 million years ago.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Charlevoix, Quebec 54 342 ± 15 K-Ar CONFIRMED Peak ring Elevated Earthquake Zone
Hotchkiss Structure, Ontario 3.9 120-330 Dated unconformity Proposed Complex Seismic research

PENNSYLVANIAN: 318 – 299 MILLION

300 million years ago, the landmass Laurentia collided with Baltica. The Appalachian mountains of eastern North America rose along the edges of the supercontinent, Pangea, and a climate shift thrust the Earth into an ice age. Map courtesy of CR Scotese, PALEOMAP Project
  • Pangea supercontinent forms as all continents collide – significant mountain building worldwide;
  • High sea levels form broad, shallow continental seas and vast coal swamps;
  • Climate hot & humid but glaciated at the poles;
  • Oxygen level 40% above today – abundant wildfires;
  • Much of the world’s coal formed in the Carboniferous;
  • Reptiles appear and diversify wildly; first ancestor of mammals appears.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Ile Rouleau, Quebec 4 <300 Geological dating CONFIRMED Complex Age based on stratigraphy

PERMIAN: 299 – 252.2 MILLION

  • Pangea supercontinent combines all major landmasses
  • Panthalassa combines all oceans except Tethys
  • Climate swings widely between hot and cold extremes
  • Huge deserts – Carboniferous swamp forests dry up;
  • Egg-laying reptiles (Sauropsids) and mammal-like reptiles (Synapsids) wildly proliferate over the land;
  • Paleozoic Era ends with Permian Mass Extinction – worst in earth’s history with 95% of all life destroyed.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Clearwater West, Quebec 32 290 ± 20 K-Ar melt rocks CONFIRMED Peak ring  Maskelynite
Des Plaines, Illinois 8 <280 Geological dating CONFIRMED Complex
Decaturville Structure, Missouri 5.5 260-323 Geological dating CONFIRMED Complex

TRIASSIC: 252.2 – 199.6 MILLION

200 million years ago, dinosaurs roamed the supercontinent Pangea, surrounded by the Panthalassic Ocean, the oceanic ancestor of the Pacific Ocean.
  • Pangea supercontinent combines all major landmasses;
  • Panthalassa combines all oceans except Tethys;
  • Climate very hot and dry with huge deserts;
  • Archosaurs wildly diversify, becoming the crocodilian Crurotarsi, the flying Pterosaurs, and Dinosaurs;
  • Dinosaurs originated (around 230 million years ago) in South America,  Pangea;
  • Marine reptiles  flourish;
  • Gymnosperm trees (conifers, ginkos; cycads) thrive;
  • Turtles, modern amphibians, modern fish, modern corals and many modern insect groups appear;
  • Period ends in large extinction.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Gow, Saskatchewan 5 <250 Radioactive decay CONFIRMED Complex Smallest currently known complex
St. Martin, Manitoba ~40 227.8 ±0.9 Ar40-Ar39 melt rock CONFIRMED Complex Maskelynite – Dauphin River diversion?
Manicouagan, Quebec 100 214 ± 1 Zircon/melt rock dating CONFIRMED Peak ring basin Maskelynite
Wells Creek, Tennessee, USA ~12 200 ± 100 Geological dating CONFIRMED Complex Shattercones
Red Wing, North Dakota 9.1 200 ± 25 Geological dating CONFIRMED Complex? Stratigraphy

JURASSIC: 199.6 – 145.5 MILLION

  • Pangea supercontinent begins to split with significant mountain-building and volcanism;
  • seas fill rift zones, Panthalassa and Tethys oceans begin shrinking;
  • Climate warm and humid with vast tropical forests;
  • The plankton that lived in the Jurassic period made our crude oil;
  • Dinosaurs dominate the land;
  • First birds arise from small dinosaurs;
  • Marine reptiles flourish;
  • Gymnosperm trees form global forests with vast ‘prairies’ of ferns.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Hartney, Manitoba 6 <190 ± 20 Geological dating PROBABLE Complex? Structurally uplifted centre
Viewfield, Saskatchewan 2.5 190 ± 20 Geological dating CONFIRMED Simple Jurassic-Triasic post-impact deposit
Cloud Creek, Wyoming 7 ~190 ± 30 Geological dating CONFIRMED Complex Chronostratigraphic
Upheaval Dome, Utah 5.5 <170 Geological dating CONFIRMED Complex Younger than the Jurassic Navajo Sandstone

CRETACEOUS: 145.5 – 65.5 MILLION

100 million years ago, Pangaea broke apart. The Atlantic Ocean poured in between Africa and the Americas. India broke away from the African continent, and Antarctica and Australia, still connected above sea level, were stranded near the South Pole.
  • Laurasia splits into North America and Eurasia;
  • Gondwana fractures into Africa, South America, Antarctica/Australia, and India (an island continent);
  • Shrinking Panthalassa becomes Pacific Ocean;
  • Atlantic Ocean forms as Tethys continues to shrink;
  • Climate warm and humid world-wide with vast forests;
  • Broad shallow continental seas stabilize temperatures;
  • Dinosaurs – in wide variety – dominate the land;
  • Birds proliferate as pterosaurs decline;
  • Flowering plants (angiosperms) appear & flourish with help from new insects;
  • Calcium-shelled marine life leave vast chalk beds;
  • Era ends when asteroid impact brings mass extinction;
  • Chicxulub impact might have triggered the enormous Poladpur, Ambenali, and Mahabaleshwar (Wai Subgroup) lava flows in the Deccan traps.

Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Miami Florida Crater/Structure ~1 ~140 After Florida Plateau deposition IMPROBABLE Complex? Underwater off Miami
Carswell, Alberta 39 115 ± 10 40Ar/39Ar Peak ring Multi-ring impact?
West Hawk, Manitoba 2.44 100 Geological dating CONFIRMED Simple No reliable age
Deep Bay, Saskatchewan 9.5 99 ± 4 Geological dating CONFIRMED Simple Flat-floored Cretaceous sediments
Kentland, Indiana ~13 >97 Geological dating CONFIRMED Complex Quarry
Howell Creek, BC ~10 90-97 Between syenites and Cardium sands IMPROBABLE Simple Circular geologic formation
Steen River Albera 25 91 ± 7 K-Ar pyroclastic vesicular rock CONFIRMED Complex Magnesioferrite MgFe2O
Lac du Bonnet, Manitoba ~3.8  75 Sedimentary cover depth PROPOSED Simple Circular magnetic anomaly
Maple Creek, Saskatchewan 6 <75 Geological & radioactive decay dating CONFIRMED Complex Disrupts Late Cretaceous rocks
Bow City, Alberta 6 <75 Geological dating PROBABLE Complex  No surface expression
Purple Springs, Alberta 6 <75 Geological dating PROBABLE Complex  No surface expression
Manson, Iowa ~35 73.8 Ar40-Ar39 melt rock CONFIRMED Central peak No surface evidence
Dumas, Saskatchewan 4 <70 Geological dating PROBABLE Simple Seismic and borehole data
Chicxulub, Yucatan, Mexico 150 66.043 ±0.011 40Ar/39Ar CONFIRMED Peak ring basin Cretaceous-Paleogene
Eagle Butte, Alberta 10 <65 Geological dating CONFIRMED Complex Shatter-coned Cretaceous rocks
Parry Peninsula, NWT 160 <65 K/T boundary timeframe IMPROBABLE Complex

PALEOCENE: 65.5 – 55.8 MILLION

The dinosaurs and the mammals appeared during the Triassic period, roughly 225 million years ago. The dinosaurs went extinct 65 million years ago. The Mesozoic Era lasted about 180 million years, and is divided into three periods, the Triassic, the Jurassic, and the Cretaceous.
  • Epoch begins with earth devestated by asteroid impact;
  • North America and Eurasia connected off and on;
  • Africa, South America, Antarctica, Australia, and India
    (an island continent) continue to separate;
  • Pacific Ocean shrinks as Atlantic Ocean widens;
  • Climate warm and humid world-wide;
  • Ferns fill post-asteroid world until forests regrow;
  • Mammals, though still small “explode” into the land niches formely dominated by the dinosaurs;
  • Large, flightless birds become top predators;
  • Flowering plants (angiosperms) flourish & spread.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes

EOCENE: 55.8 – 33.9 MILLION

By 50 million years ago, dinosaurs were extinct from the Earth. Continental fragments collided, pushing up mountain ranges still existing today. The collision of Africa into Europe gave rise to the Alps in Europe, and the collision of India into Asia formed the Himalaya. Birds and mammals began to expand in number and diversity.
  • Continents continue to separate; Africa & India (an island continent) drift north towards Eurasia;
  • Pacific Ocean shrinks as Atlantic Ocean widens
  • Climate extremely hot & humid; greenhouse conditions allow for tropical forests from pole to pole;
  • Mammals multiply, Primates  proliferate, Whales appear in oceans;
  • Birds are top predators; many modern families appear;
  • Grasses appear but cling to river banks & lake shore;
  • Epoch ends with mass extinction.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Montagnais, off Nova Scotia 45 50.5 ± 0.76 K-Ar, 40Ar/39Ar and Rb-Sr CONFIRMED Complex Submerged south of Nova Scotia, Canada
Victoria Island, California 5.5 37-49 Drilling data PROPOSED Simple Geological dating
Wanapitei, Ontario 3 to 7.5 37.2 ± 1.2 K/Ar, Ar40-Ar39 melt rock CONFIRMED Simple – Possible flat-floored? Maskelynite – L or LL chondrite projectile
Mistastin, Labrador 28 36.6 ± 2 Ar40-Ar39 melt rock CONFIRMED Central peak basin Maskelynite
Chesapeake, Virginia ~85 35.5 ± .3 Geological dating CONFIRMED Complex Coesite in suevites

OLIGOCENE: 33.9 – 23 MILLION

  • Continents continue to drift to present positions;
  • Africa and India continue to drift into Eurasia;
  • South America, Antarctica & Australia isolated;
  • Pacific Ocean shrianks as Atlantic Ocean widens;
  • Climate warm but begins to cool;
  • Mammals continue to flourish & grow larger;
  • Apes first appear;
  • Grasses spread; deciduous trees & shrubs spread.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes

MIOCENE: 23 – 5.3 MILLION

  • Continents continue to drift to present positions;
  • Africa collides into Eurasia forming the Alps;
  • India collides into Eurasia forming the Himalayas;
  • The Rockies & Andes continue to rise
  • Mediterranean Sea dries up;
  • Global mountain building cools climate; icecaps form;
  • Almost all modern mammal & bird families are present;
  • Grasslands, deciduous trees & shrubs spread;
  • Modern carnivore mammals spread;
  • Hominoid apes flourish and diversify;
  • Isolated South American & Australian marsupials thrive;
  • Kelp forests seals and otters appear in oceans.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes

PLIOCENE: 5.3 – 1.8 MILLION

  • Continents & oceans in current position
  • North & South America connect via Isthmus of Panama, altering global temperatures & currents;
  • Huge Gibraltar waterfall refills Mediterranean Sea;
  • Climate cool, dry and seasonal;
  • All modern plants & animals families present, land & sea;
  • Grasslands, deciduous trees & shrubs spread as tropical forests recede;
  • Land bridges cause migration & mixing of animal species;
  • Carnivores thrive & diversify;
  • First hominids – australopithecinesappear;
  • Many upright, tool-using hominids by end of epoch.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes

PLEISTOCENE: 1.8 MILLION – 10 THOUSAND

The formation of the isthmus connecting North and South America and the split of the Australian continent from Antarctica changed global ocean currents and climate. Ice sheets carved out the Great Lakes of the United States and Canada just 20,000 years ago. Since then, warmer temperatures have melted ice, and sea levels have risen. Map courtesy of CR Scotese, PALEOMAP Project
  • Continents & oceans in current position;
  • Four major glacial advances (ice covered up to 30% of Earth’s surface) followed by interglacial warming;
  • Sea levels drop & rise as glaciers advance and melt;
  • Climate cold & dry world-wide;
  • Epoch ends in mass extinction; esp of megafauna;
  • All modern plant & animal families present, land & sea;
  • Large mammals (megafauna) thrive;
  • Tool-using pre-humans appear in Africa & spread throughout the Old World;
  • Neanderthal humans appear then disappear;
  • Modern humans (Homo sapiens) first appear.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Pingualuit, Quebec 3.44 1.4 ± 0.1 Ar40-Ar39 melt rock CONFIRMED Simple Overflight of Pingualuit Crater
Carolina Bays, NC Various ~0.0129-0.14 Not firmly quantified PROPOSED Simple Younger Drias black mat
Corossol Structure, Gulf of St. Lawrence 4.0 ~0.012 14C age shells in sediments PROPOSED Complex Underwater Gulf St. Lawrence
Bloody Creek, Nova Scotia 0.350 X 0.420 ~0.012 Geological dating PROBABLE Simple  Elliptical basin
Jocko, Ontario >0.2 <0.012 Created in glacial remains IMPROBABLE Simple Ground Exploration Video
Plevna/Tomvale Structure, ONTARIO ~0.01 <0.012  Created in glacial remains IMPROBABLE Simple

HOLOCENE: 10 THOUSAND – PRESENT

  • Continents & oceans in current position; sea levels rise;
  • Climate warming partly due to human industrialism;
  • Mass extinction in progress due to human proliferation;
  • Human civilization dominates most Earth ecosystems;
  • Epoch opens with many Pleistocene animals extinct;
  • Few new plants or animals appear;
  • Human selction supercedes natural selction – humans favor beneficial plants and animals; neglect others;
  • Human culture significantly alters natural landscape;
  • Human genetic technology manipulates Earth’s life at the most fundamental level.
Name Diameter (km) Age (megayears) Dating method Morphological type Notes
Barringer, Arizona 1.19 0.049 ± 0.003 Radioactive decay CONFIRMED Simple Jointed
Whitecourt, Alberta 0.036 0.00113 14C dating of charcoal CONFIRMED Simple Medium octahedrite (Om) IIIAB
Merewether, Labrador 0.19812 (largest of three) 0.00087? Sediment depth IMPROBABLE Simple Possible methane explosion
Charity Shoal, Lake Ontario ~1  ? PROPOSED Simple underwater Lake Ontario Negative magnetic anomaly
Charron Lake, Manitoba >4.5  ? PROPOSED Simple Negative magnetic anomaly
Eclipse Lake, Labrador small ~1.5  ? IMPROBABLE Simple – Possible flat-floored Two possible structures
Eclipse Lake, Labrador large ~6  ? IMPROBABLE Complex  Two possible structures
Kakiattukallak Lake, Quebec 3 – 6  ? PROPOSED Simple Possible Multiple Impact?
Lac de Courval, Quebec ~1.6  ? PROPOSED Simple Circular lake
Lac La Moinerie (north), Quebec 1.8  ? IMPROBABLE Simple Circular structure

50 MILLION YEARS IN THE FUTURE