ABSTRACT

Radiographic examination of cores taken at the entrance of a Georgia tidal inlet revealed three texturally and structurally different types of mud layers. Type I mud layers are composed of laminations of day-size detritus that occur as flaser, wavy and lenticular bedding. Type II mud layers are composed of foresets and sand-size fecal and organic detritus that also occur as flaser, wavy and lenticular bedding. Type III mud layers are composed of foresets of mud pebbles and occur as wavy lenticular bedding.

Mud-layer types form in response to hydraulically different depositional processes combined with the local availability of mud-grain sizes. Examination of textures and structures in these mud layers indicates that grains which constitute mud layers are transported and deposited from the traction load as well as the suspension load. In some areas, deposition from the bedload (traction load)is considerably more pronounced than deposition from suspension load. Type II and III mud layers result from bedload deposition which does not necessitate a period of slack-water in the tidal cycle or a specific set of conditions of wave activity, suspended-matter concentration, and current velocity.