Sedimentologic relevance of convulsive geologic events

Convulsive (or catastrophic) geologic events undeniably have been part of the history of our planet throughout geologic time. Convulsive events are violent disturbances of regional or even global extent. Some types, such as giant storms or explosive volcanic eruptions, are commonplace in the geologic record; others, such as major bolide impact, are exceedingly rare. The sedimentologic record of convulsive geologic events differs in preservation potential depending largely on whether the effect occurs within an active depositional basin. In some settings, such as deep sea fans, a significant part of the deposit may result from large and violent events. The record within the sediment of a convulsive event may be either dramatic or subtle; the degree of distinctiveness therein may not be an accurate guide to the overall consequence of the event on a accurate guide to the overall consequence of the event on a planetary scale. Because convulsive events typically produce a brief, but significant, disturbance over a broad area, their sedimentologic consequences provide excellent chronologic markers in the stratigraphic record, in some cases on a global scale. Perhaps most importantly, the recognition of the results of convulsive events in the geologic record forces one to consider processes operating atmore » a scale that may be inconceivable in the context of our present-day world.« less