Institute of Oceanography, Old Dominion College, Norfolk, Va.
GRADED RHYTHMIC BEDDING IN THE CAPE EEAR FORMATION, CAROLINA COASTAL PLAIN
Version of Record online: 14 JUN 2006
Volume 11, Issue 1-2, pages 39–52, October 1968
How to Cite
HERON, S. D., SWIFT, D. J. P. and DILL, C. E. (1968), GRADED RHYTHMIC BEDDING IN THE CAPE EEAR FORMATION, CAROLINA COASTAL PLAIN. Sedimentology, 11: 39–52. doi: 10.1111/j.1365-3091.1968.tb00839.x
- Issue online: 14 JUN 2006
- Version of Record online: 14 JUN 2006
- (received April 15, 1968); (Resubmitted August 12, 1968)
The Cape Fear Formation rests on basement rocks in the Cape Fear River valley of the North Carolina Coastal Plain. It consists primarily of graded muddy sand—sandy mud couplets. A typical sequence for each couplet starts with a disconformity, followed by a basal gravelly sand with megaclasts of quartz and clay pebbles, cross-bedded sand, and finally a structureless mud bed. Fossils are absent. The sand fraction is poorly sorted and the sediment has a clayey texture. Structures and textures suggest that each couplet is the product of a current waning from an upper flow regime, to the lower part of a lower flow regime. Turbidity current and fluvial origins are considered. Cross-bedding and textural criteria indicate that normal, low-density currents are responsible for at least part of the typical sequence. A normal fluvial origin is rendered less likely by the absence of mud cracking, root casts, and textural criteria of a partitioned subaerial environment. Stratigraphic and geochemical considerations suggest that the formation may have been deposited in estuaries or coastal lagoons; if so, the stratification may record sedimentation during the periodic flushing of saline water by river floods.