Bridgeton Formaticust — Local Details. 



27 



The unevenness of its base may be seen at various points, as 

 at the headwaters of Deep Run, east of Dilks Mill. Three- 

 fourths of a mile east of this mill, and a mile southwest of Fries- 

 burg-, the base of the Bridgeton has an altitude of about 120 

 feet. South of this point, the base runs down to 90 feet within 

 a mile. The low level is interpreted as representing a pre- 

 Bridgeton valley, but here, as in some other cases, it is possible 

 that the low level of the Bridgeton material is the result of down- 

 slope creep since the adjacent valleys were excavated. 



'Friesburg 



Detretown 



S ea-level 



LEGEND 



heet 

 20.O 





S C ALE S 



Horizontal scale. 

 1 .2 



i 1 



3Miles 



MIOCENE COHANSEY BRIDGETON < 



Fig. 12. 

 Relations of the Bridgeton along a section from Friesburg to Daretown. 



About Aldine, the base of the Bridgeton formation is notably 

 irregular. At Aldine it has an altitude of about no feet, but 

 half a mile to the west, 120 feet. Half a mile north, there is 

 a headland at Ballinger's Mill, which has an elevation of 120 

 feet. The mill pond has an elevation of 84 feet, and the base 

 of the Bridgeton is but a few feet above it. The general rela- 

 tions of the formation are shown in Fig. 12. To the west, 

 east, and south of Aldine, the base of the formation is not below 

 .100 feet, and is in many places 100 to 120 feet, so that the old 

 valley where the base of the Bridgeton appears at 90 or below, 

 seems to have had its outlet to the west. 



Constitution. — To the west, the constitution of the formation 

 is normal, but in the region about Bridgeton it is difficult, in 

 many places, to distinguish the Bridgeton formation from the 

 Cohansey which underlies it. Locally most of the material of 



