Two Pleistocene channel-systems are recognized in New Castle County, (1) a system of straight channels located in the area north of the Chesapeake and Delaware Canal and (2) a braided system occupying the area south of the Canal.
Fluctuations of the flow regime of Pleistocene streams were frequent as evidenced by sedimentary structures and widespread distribution of gravels in the channel deposits.
During high stream flows most of the study area was submerged, while during low flows large interstream areas and islands emerged.
The transporting agents of the Pleistocene sediments were primarily melt-water streams originating below glaciers which at times advanced to within 100 miles north of New Castle County. Thus, the age of the deposits is thought to be glacial, but there is no indication as to which glacial stage they belong. However, the channels appear to have been formed contemporaneously by a major distributary system.