Pensauken Formation — Local Details. 135 



wick and Metuchen, though containing less shale. These hill 

 cappings are probably Pensauken, though not of the normal 

 phase. They suggest the first of the hypotheses noted above. 



A mile and a quarter northwest of Franklin Park there is a 

 130-foot area mantled by gravel, and half a mile farther north- 

 west there is another area of gravel at the same (maximum) 

 elevation. In all these places the gravel is lower on the north 

 slopes of the elevations than on the south. This may be the 

 result of displacement, though this is not clear. 



West of the Millstone River. — West of the Millstone River, 

 and a mile northwest of Griggstown, there is an area of gravel 

 and loam at about 125 feet. The gravel here differs from that 

 to the east, in that it has more small quartz pebbles — rather of 

 the Beacon Hill type. East of the river, sandstones, quartzite, 

 shale, etc., are more prominent. South of Blawenburg, at 120 

 to 130 feet, there are remnants of gravel like those about Griggs- 

 town and Franklin Park. 



The above remnants at 120 to 150 feet are perhaps all Pen- 

 sauken, and indicate a general mantling at this level. So far 

 as this region is concerned, there might be doubt as to the age 

 of the material; but if the preceding interpretations are correct, 

 Pensauken occurs at 160 to 170 at Jamesburg, 165 at Old 

 Bridge, 150 at Rhode Hall, and at 160 feet north of Somerville. 

 In view of this distribution, it is not unreasonable to refer all 

 these remnants to the Pensauken. An alternative view is that 

 the high remnants noted are remnants of the Bridgeton forma- 

 tion, the base of which has an elevation of 130 to 140 feet near 

 Glassboro, and 90 feet at Bridgeton. If, however, this dip were 

 carried northward, it would carry the base of the formation far 

 above the level of these gravels from Franklin Park to Blawen- 

 burg. Another alternative is that the gravels referred to are of 

 various ages, and not referable to any one distinct stage of 

 deposition. 



One of the most remarkable areas of the Pensauken forma- 

 tion occurs at Kingston on the east side of the Millstone River 

 just south of the gap in the Rocky Hill range. In coarseness, 

 proportion of crystalline material, and decay of bowlders, this 

 deposit is unique. Many bowlders 1 to i J / 2 feet in diameter are 



