- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
"Theories of varying complexity which have sought to explain cyclic sedimentation are briefly summarized, and it is suggested that the two basic requirements are a slowly subsiding sedimentary basin and more or less regular eustatic changes of sea level. The former will decide the geographical location. The latter could be a natural, periodic and world-wide consequence of the combination of the continuous effects of sedimentation and isostatic or orogenic movements of the sea floor."