THE MUDLINE: VARIABILITY OF ITS POSITION RELATIVE TO SHELFBREAK

The mudline, the depth of substantially increased silt and clay content and the level below which deposition prevails on continental margins, often occurs near, but is only rarely coincident with, the shelf-to-slope transition. An evaluation of the mudline off the U.S. Mid-Atlantic States and northern Gulf of Mexico highlights marked differences between depth and position of this horizon and those of the shelfbreak, and is summarized in four relationships. Type I = Off Cape Hatteras and portions of the west Florida shelf, offshelf transport of sand-size material results in a mudline position well below the shelfbreak. Spillover at Cape...