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