Stratigraphic and paleontologic evidence from mid-Carboniferous (Namurian) basin and
shelf successions in widely scattered parts of the world indicates that a major eustatic event
occurred about 330 Ma.  The event began with a regression that is recorded in most shelf
sequences, the regression was followed by a brief transgression about 328 Ma, and the event
ended with a transgression that flooded large shelf areas about 325 Ma.  The Mississippian-
Pennsylvanian unconformity in North America is, a well-known product of this event, but
equally prominent and contemporaneous unconformity surfaces are also present in Europe,
North Africa, and elsewhere.  The event is believed to have caused numerous extinctions, and
it resulted in marked fluctuations in faunal diversity.