Inclined and seemingly deformed sedimentary features similar to those just described 

 were found by Knott and Hoskins (1968) on the shelf south of Martha's Vineyard. The 

 inclined beds appear (Fig. 13 from Knott and Hoskins, 1968) to be about 125 feet thick and 

 overlain by flat-bedded material 30 to 60 feet thick. Because of apparent folding and 

 overthrusting the authors have attributed the anomalous bedding to ice-push deformation, 

 due to southward-directed glacial transport. Thus, they conclude the strata south of 

 Martha's Vineyard may mark the southern limits of Pleistocene glacial advance in the 

 eastern Long Island region. Fuller (1914) reported the presence of extensive isoclinal folding 

 of Cretaceous strata and the Pleistocene Gardiners Formation on Long Island which he also 

 attributed to ice pressure. Fuller also noted that the clay beds, because they were more 

 coherent and better able to transmit lateral stress, remained intact during compressional 

 folding; incompetent sand and gravel strata were incapable of transmitting stress and were 

 squeezed into structureless masses. Keeping his observations in mind, it is difficult to believe 

 that unconsolidated outwash materials, about 125 feet thick, could transmit the pressures 

 over several kilometers to result in the structures described by Knott and Hoskins (1968) 

 and later by Uchupi (1970). While it is plausible that some glaciers transgressed south of the 

 terminal moraine on Martha's Vineyard and were the cause of local sediment deformation, 

 the presence of apparent buried stream channels and stratified sediment on the Knott and 

 Hoskins (1968) figures strongly suggest that the strata may be sedimentary structures built 

 by outwash-laden meandering streams which drained the glaciers and flowed onto the shelf. 

 However, if structural deformation is truly pervasive, the inclined structures are more likely 

 slump structures, resulting from instability due to rapid depositional loading of sediment on 

 an unstable sloping surface. Some trigger mechanism could then cause gravity slumping. In 

 any case, the inclined bedding structures east of Sandy Hook appear to owe their origin to 

 depositional processes, possibly related to a cataclysmic event, such as rupture of major 

 proglacial dams which periodically occupied the Hudson Valley or to fluvial processes 

 operative at the confluence of the ancestral Raritan and Hudson Rivers. (Connally, 1972.) 



A third type of sedimentary bedding shown in Figures 5, 7, and 8, consists of nearly 

 horizontal and sometimes seaward dipping Pleistocene and Holocene silt, sand and gravel 

 sediments. Because of the lack of sharp acoustic contrast between these materials the 

 seismic records show only faint hints of continuous bedding. The bedding surfaces which 

 show on the geophysical records probably mark an interface between two materials with 

 markedly different mass properties. There is a perceptible increase in thickness of the 

 Pleistocene-Holocene sands from the southern part of the study area, offshore from Long 

 Branch toward the south shore of Long Island at Rockaway Beach. (See Figure 5.) Because 

 of the nature of the material and the proximity of the moraines and outwash plains on the 

 north side of Long Island it seems plausible that this material on the shelf is primarily fluvial 

 outwash sediment which during Pleistocene time was deposited on top of the Coastal Plain 

 strata which had been eroded by rivers in the area. 



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