Shrewsbury Rocks are a positive topographic sea floor feature at the southern end of the 

 study area, immediately south of the Shrewsbury River. (See Figure 4.) They trend in a 

 northeast orientation and form a demarcation line separating two markedly different 

 geologic and physiographic provinces. North of Shrewsbury Rocks sea floor morphology is 

 irregular and random except for the obvious submarine channels and the even contour line 

 spacing south of Rockaway Beach. Sea floor topography south of Shrewsbury Rocks 

 follows a similar northeast fabric of alternating ridge and swale structures. Shrewsbury 

 Rocks extend about 6 miles seaward from the shore to where they have been abruptly 

 truncated by the Hudson Channel. It is also interesting (Fig. 4) that the Highland Channel 

 turns sharply east and joins the Hudson Channel immediately north of where the Hudson 

 River has breached Shrewsbury Rocks. Apparently the Shrewsbury Rocks persisted as a 

 barrier during Pleistocene and had a definite influence on diverting the course of drainage of 

 the Raritan River and possibly the Hudson River. 



Cholera Banks is another prominent topographic high located about 13 miles east of the 

 New Jersey shore (Fig. 4) on the seaward flank of the Hudson Channel. Because of its 

 northeast strike alignment with Shrewsbury Rocks, it very likely represents an eastward 

 extension of one or more resistant Coastal Plain strata; however, no geophysical data are 

 present in this area to support these conclusions. 

 2. Shallow Subbottom Structure. 



Three distinct types of sedimentary bedding are evident from the geophysical records 

 which allow a maximum of about 300 feet of subsea floor resolution. The first bedding type 

 has the character of Coastal Plain strata which have a regional dip of about 1 on 80 (65 feet 

 per mile) to the southeast. Energy penetration deeper than the first reflecting surface below 

 the water-sediment interface is marginal so it is difficult to delineate detailed vertical 

 stratigraphy. Records south of Shrewsbury Rocks show a buried surface of acoustic 

 contrast, which may correlate with the Tl reflector traced across the shelf south of New 

 England by Garrison (1970). Garrison assumed the Tl to be the contact between the 

 Paleocene Vincentown Formation and the Miocene-Pliocene Cohansey Formation. Based on 

 subsea depth and relative position in Coastal Plain stratigraphy this assumption agrees with 

 our geophysical records. 



Seismic profile Line 37 (Figs. 2 and 5) extends south-north from Long Branch, and 

 shows the regional southeasterly dipping nature of the Coastal Plain strata and how they 

 crop out on the sea floor south of Long Branch exhibiting about 15 feet of sea floor relief . 

 This sea floor expression shown on the seismic records matches exactly with the location of 

 Shrewsbury Rocks and is along strike (on line) with Cholera Banks, farther to the northeast. 

 Because Shrewsbury Rocks is in apparent alignment with the Cretaceous-Tertiary contact on 

 land it is reasonable to hypothesize that these outcropping beds are either the uppermost 

 Cretaceous Tinton Formation (an indurated sandstone) or the early Tertiary Hornerstown 

 Formation (a glauconitic sand body). 



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