Abstract The late Wisconsinan and Holocene coastal evolution of southern Lake Michigan contrasts with the coeval history of ocean-coast settings. Multiple transgressive and regressive events occurred, and rates of lake-level change were often greater than the most rapid eustatic sea-level changes. A succession of lower high-lake maxima is recorded in mainland beaches, spits, and beach-ridge/dune complexes across the Chicago/Calumet lacustrine plain. The plain, which extends approximately 120 km from north of Chicago to the Indiana-Michigan border, was the sink for net-southerly littoral transport. During the high-lake phases between 14.5 ka and about 3.5 ka, littoral transport from the eastern and western lake shores terminated in separate spits on opposite ends of the lacustrine plain. Since about 3.5 ka, littoral transport converged along the southern shore. Gradual changes in coastal geomorphology, brought about by littoral processes acting within an overall trend of lake-level decline over the past 2,500 years, formed the modern coastal geography. The Chicago River was transformed from a westward- to an eastward-flowing drainage; littoral-sediment accretion resulted in an extensive beach-ridge/dune complex and a 35-km stream-mouth deflection forming the Grand Calumet River. A model for the coastal sedimentary evolution during the transgressive phases indicates minimal-sediment supply until rate of lake-level change declined and a peak lake level was reached. Wave erosion along the glacial-bluff lake margins could then supply the littoral-transport system. The overall depositional history of the south Lake Michigan coast is that of a regressive and progradational system.

Abstract Humans are fascinated with the proposition that there are artifacts of ancient civilizations below sea level. The question arises, “How feasible is it for twentieth and twenty-first century humans to find extensive remains of ancient civilizations that were submerged by the Holocene rise in sea level?“ The interest of society in marine archaeology and treasure hunting surged in recent years as a result of several spectacular discoveries. Among these were the 1972 discovery of the U.S.S. Montitor off Cape Hatteras (oldest iron-clad warship), the H.M.S. De Braak off Cape Henlopen (a British warship purported to be carrying as much as $500 million worth of booty), and the H.M.S. Titanic off the Canadian Maritime Provinces. Although these are not prehistoric finds, they raised public support for archaeological research in general. In this chapter we synthesize the state-of-the-art of paleogeography of known prehistoric archaeological sites in the coastal zone, as well as those that presumably lie on the submerged portion of the continental shelf of North America's mid-Atlantic Bight (Fig. 1). In the Americas, according to Deetz (1988), "prehistoric"refers to any material remains prior to A.D. 1492. On the peninsula of Delaware, Maryland, and Virginia (Delmarva), Thomas (1974) defined prehistoric periods approximately as cited in Table 1. Where necessary, this approximate period nomenclature for early humans in the area is used. Coastal and shallow-marine archaeological sites are reported from around the world (Edwards and Emery, 1977; Fleming, 1983; Kraft and others, 1983b, 1985). An additional site is described here and related

Abstract: Transgressive barriers of the embayed Atlantic and Gulf coast are generally similar in overall form, processes, and landward migration in response to relative sea-level rise, but they vary greatly in potential sources and volume of sand supply. Delaware's transgressive barriers vary in thickness from 25 m to less than 5 m; dunes may rise to 20 m above sea level, whereas barrier-spit and inlet sand reach depths of 10–18 m below sea level. Widths vary between 0 m at eroding headlands and 4–6 km near tidal delta and spit complexes. A complete Holocene paralic sequence for Delaware includes a basal sand and/or gravel overlain by marsh, lagoon, and barrier lithosomes. Shoreface erosion, as the barrier lithosome moves landward, occurs to an average depth of 10 m, with about 50% of eroded sediment derived from Holocene and Pleistocene lagoonal mud outcrops. Since the suspended material is carried out of the shoreface, its removal requires a re-evaluation of the volumetric model commonly inferred from the Bruun mechanism. Also, the third dimension of longshore transport of coarse material needs to be considered. As transgression continues, the ravinement surface exposes lagoonal sediments, marsh mud, irregularly shaped basal remnants of the Holocene barrier lithosome, or varied Pleistocene strata. These are then blanketed by varying thicknesses of inner-shelf sand. Ultimately, the transgressive barrier and associated paralic environments migrate landward to peak interglacial positions where the entire transgressive record may be preserved. A relatively complete vertical sequence of transgressive coastal lithosomes might also be preserved at the outer edge of the continental shelf at glacial sea-level minima. Thus, the optimal chance for total preservation of a transgressive coastal lithosome sequence lies at the extremes, landward at the peak interglacial when eustatic sea-level rise stops and the coastal lithosome sequences become stranded, and possibly on the outer edge of the shelf as deglaciation begins and there is rapid rate of sea-level rise.