The Columbia deposits of Delaware form a sheet of sand with a maximum thickness of approximately 150 feet which covers most of the Coastal Plain portion of the State. The dispersal pattern, deduced from foreset dip directions of cross-bedding, indicates that the sediment entered the study area from the northeast, i.e., from the direction of the valley of the Delaware River between Wilmington and Trenton, and spread south and southeast over Delaware.
Please give proper credit to the Delaware Geological Survey.
Jordan, R.R., 1964, olumbia (Pleistocene) Sediments of Delaware: Delaware Geological Survey Bulletin 2 ,
Delaware Geological Survey
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