560 HENRY B. KUMMEL 
Lockatong argillite terminates abruptly where the fault crosses 
the strike of its beds. The height and prominence of the escarp- 
ment north of Skillman station is due to the contrast in hardness 
of the Lockatong and Brunswick shales brought into juxtapo- 
sition by the fracture. 
The dislocation has been sufficient to bring to the surface 
the upper part of the Stockton beds, and place them side by 
side with the middle layers of the Brunswick shales. On the 
basis of the above estimates of thickness the throw cannot be 
less than 10,000 feet. The hade of the fault cannot be deter- 
mined, since the fracture is nowhere exposed in section and its 
location can rarely be determined within fifty yards. North of 
Flagtown, where the Brunswick shales occur on both sides of the 
fracture, its course could not be determined. 
Flemington fault——The course of this fault previously noted 
by other workers" is best seen by reference to the map. It is 
located in the bluffs of the Delaware River by the juxtaposition 
of the coarse arkose conglomerate (Stockton) with the black 
argillite (Lockatong) a mile or more south of Stockton. The 
line of dislocation is concealed by the talus of a small ravine. 
From this point it extends in a northeasterly direction for three 
miles, thence curving a little to the north so as to pass east of 
Headquarters, southeast of Sand Brook and a mile west of the 
center of Flemington. For much of this distance it extends 
along the foot of the Hunterdon plateau escarpment.? For sev- 
eral miles north of Flemington its exact location becomes doubt- 
ful owing to the similarity of the adjoining beds, but one or 
perhaps both of the two faults along the border west of Cushe- 
tunk Mountain mark its northern extension. There is some rea- 
son for believing that the trap of Round mountain, south of Cushe- 
tunk Mountain, has ascended along the fracture, but this is not 
conclusively proven. 
The evidence of this fault is as complete as in the case of 
*LEWIs, DARTON, NASON, LyMAN, and others. 
?On a “conjectural” map of the Newark formation of New Jersey (Lyman, Pa., 
Geol. Surv. Summary Final Report, Vol. III, Pt. II, Plate 597, also Proc. Am. 
