• 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
Crooked Creek, Missouri ~7 ~348 – 323 Geological dating CONFIRMED Complex Serial impact event?
Charlevoix, Quebec 54 342 ± 15 K-Ar CONFIRMED Peak ring Elevated Earthquake Zone
Weaubleau, Missouri 19 320 – 340 Geological dating PROBABLE Complex Ring-like drainages