744 The American Naturalist. (August, 
of pebbles to matrix is usually large, but there is local variation in this 
regard. The pebbles are mainly well rounded, but some subangular 
ones occur. They are mostly all of quartz, and white or pinkish in 
color. No quartzite pebbles were observed. In this characteristic the 
Green Pond Conglomerate differs greatly from the Skunnemunk con- 
glomerate, but otherwise they are very similar. The thickness of the 
Green Pond conglomerate varies. In New York there are not over 60 
feet, but in New Jersey it will probably be found to average about 150 
feet in its greatest development in Green Pond and Copperas Mount- 
ains. Owing to its extreme hardness and massiveness, it give rise to 
high, rocky ridges with precipitous slopesin greater part. Green Pond, 
Copperas, Kanouse and Bowling Green Mountains are the most prom- 
inent of these, and they occupy an area of considerable size in New 
Jersey. South of the south end of Green Pond Mountain west of 
Dover there are outliers of conglomerates and sandstones probably of 
this age, which are described by book in the ‘ Geology of New Jersey ’ 
1868. 
“ In the vicinity of Cornwall Station the conglomerate lies on Hud- 
son shales; Pine Hill, on Cambrian limestone, at least in part; in Ka- 
nouse Mountain, on slates possibly of Hudson age, northward, and on 
Cambrian limestone southward ; in Green Pond, Copperas and Bowl- 
ing Green Mountains it lies directly on the crystalline rocks. The con- 
tact with the crystalline rocks is exposed along the upper part of the 
eastern slopes of Copperas Mountain, and the surface is a relatively 
level one. Small enclosed areas of the crystallines are bared by erosion 
of the conglomerate along the two anticlinals south of Newfoundland, 
and I find that gneiss extends to within half a mile of the depot in the 
western flexure. Along the axis of the eastern flexure, gneiss extends 
to and under Green Pond and down the gorge of the outlet of the pond 
to the end of Copperas Mountain. Along these anticlinals no actual 
contacts were found, but from many exposures in its vicinity the rela- 
tive eveness of the floor was clearly apparent. In the Bowling Green 
Mountain the conglomerate is wrapped around the northern end of a 
ridge of gneiss, but its contact relations were not observed. 
“The age of the Green Pond conglomerate and quartzite is approx- 
imately the same as Shawangunk grit and Oneida conglomerate, and 
probably they also represent all or a portion of the Medina. They are, 
at any rate, the representatives of the great arenaceous sedimentation 
at the beginning of the UpperSilurian. The evidence of their position 
is mainly their intimate relation to the Helderberg limestone through- 
out and the fact that they overlie the Hudson shales in New York and 
