98 Quaternary Formations of Southern New Jersey. 



While an exceptionally thick section (27 feet), its composition 

 is characteristic of the formation in the valleys of tributary 

 streams. 



Between Raccoon and Mantua creeks. — Very considerable beds 

 of arkose Pensauken are found north and west of Swedesboro, 

 between Rulons and Clarksboro, on the Swedesboro Plain. At 

 the northwest, the base of the formation has an altitude of 20 

 to 50 feet, and at the southeast, 50 to 90 feet. In places there 

 are 20 to 30 feet of arkose sand, with only occasional seams 

 of pebbles, among which shale and bits of crystalline rock occur. 

 If the very base of the formation is excepted, there is more 

 gravel in its upper than in its lower part. The arkose phase of 

 the Pensauken stops promptly at an elevation of about 90 feet. 

 This appears to have been the upper limit of aggradation by the 

 Delaware. 



About Rulons and Asbury Station the formation is at least 30 

 feet thick in places (Fig- 44). It must have been thicker still 

 originally, for the top probably reached an altitude of 80 or 

 90 feet. West of Asbury Station its base runs down to 30 feet 

 or so. Considerable patches of the arkose phase of the forma- 

 tion occur about Tomlins and Mickleton, and the non-arkose 

 phase runs up to 100 or even 108 feet a mile east of Mickleton. 

 The former phase is well developed about Clarksboro, where it 

 is exposed in various pits. 



Northeast of Swedesboro, some non-arkose gravels of un- 

 certain age cap elevations at 114 and 115 feet, the gravel be- 

 ing cemented to some extent. The slopes between these hills 

 and the arkose Pensauken at lower levels are nearly bare Cre- 

 taceous, and represent the old pre-Pensauken scarp, at the east- 

 ern border of the Swedesboro Plain. 



East of Swedesboro, the non-arkose material classed as Pen- 

 sauken occurs at various heights, and may be of different ages. 

 If the arkose phase was built up by the Delaware to the present 

 level of 80 or 90 feet, the contemporaneous deposits of Raccoon 

 Creek should have risen perhaps to 100 or no feet at Mullica 

 Hill. Most of the gravel and sands classed as Pensauken east 

 of Swedesboro and north of the Raccoon Creek lie between the 

 levels of 80 and 100 feet. The 114 and 115-foot patches east of 



