A uniformitarian hypothesis is possible to explain the great Permian-Triassic life extinction event. Unlike the recent "catastrophic" explanations for the Mesozoic-Cenozoic extinctions, this hypothesis does not depend upon extraterrestrial intervention.

The dominant worldwide event at the close of the Paleozoic was the formation of Pangea. The Mesozoic witnessed the sundering of this supercontinent and the formation of the modern continental masses and oceans.

The areas covered by the waters of the Paleozoic oceans surrounding Pangea either were incorporated onto the fringing continents or were subducted. New oceans, which became the present oceans, were forming in the Mesozoic in the areas where the combined continental masses were splitting apart.

If these 2 events were in part simultaneous and yet physically separated in such a way that the waters in the newly forming oceans did not connect with the water in the closing oceans, almost complete extinction of all earlier marine life forms would result.

Radioactive dating of the present ocean floor indicates that the Paleozoic floor was eliminated, and new ocean floor began to form in the Mesozoic. Chemical dating of present ocean water indicates that its time of origin is approximately the same as that of the present ocean floor.

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