The following description was published in RI76 Stratigraphy, Correlation, and Depositional Environments of the Middle to Late Pleistocene Interglacial Deposits of Southern Delaware, Ramsey, K.W., 2010:
The Assawoman Bay Group consists of the well-sorted sands, silts, and clays of the Omar, Ironshire, and Sinepuxent Formations found adjacent to and inland of the Atlantic Coast of Delaware and Maryland. These deposits in Delaware and Maryland were named from oldest to youngest: the Omar Formation (Jordan, 1962, 1964), the Ironshire Formation (Owens and Denny, 1979), and the Sinepuxent Formation (Owens and Denny, 1979).
The Assawoman Bay Group consists of transgressive deposits that were deposited along the margins of an ancestral Atlantic Ocean during middle to late Pleistocene highstands of sea level. It is named for the Little Assawoman Bay in Delaware and the Assawoman Bay in Maryland in the vicinity of where the Omar, Ironshire, and Sinepuxent Formations are best developed. In Delaware, the Assawoman Bay Group extends south of Indian River Bay to east of Gumboro. In Maryland, it is mapped south and west of Salisbury (Owens and Denny, 1979). It extends east of Salisbury into the Virginia portion of the Delmarva Peninsula (Mixon, 1985).