About This Item
Share This Item
"Event beds"--strata attributed to rapid, episodic sedimentation--are recognizable throughout the geologic column. Although these beds range widely in age and depositional setting (deep-sea turbidites to shelf "tempestites"), a few diagnostic features are common to all event beds (erosional base grading up to a "pelagic" top). Few morphological features of these beds have changed through time; however, recent theories of increased infaunalization through time predict that fewer event beds would be preserved after the infaunal explosion of the Jurassic and suggest that the conditions under which post-Jurassic event beds are preserved must differ in some way from preservation of pre-Jurassic beds. A survey of recent literature on event beds, ranging in age from Precambrian o Holocene, reveals no shift in major patterns of preservation, although documentation of Tertiary to Holocene strata is sparse, probably because of artifact effects (e.g., relatively small volume of outcrop). Preservation of event beds is not so dependent on depositional setting as it is on the frequency and intensity of the event and the presence of infaunal burrowers.
End_of_Article - Last_Page 240------------