BELLVALE FLAGS. 373 



There is a longitudinal valley along the boundary of the cr3"stalline rocks 

 at the western mouth of the gap, which is apparently underlain by red 

 slates, for this member outcrops along the slopes southward. Here also 

 for some distance the shales are underlain b}' a few feet of flags. 



In the southern gap, which crosses Bearfort mountain about four miles 

 south of the southern end of Greenwood lake, the exposures are some- 

 what interrupted by swamp-filled depressions and by drift. Beginning 

 on the east side, there is a basal series of red quartzitic sandstones and 

 slates which lie along the eastern side of the middle ridge. They give 

 place above to a thin, local series of gray flaggy beds which are overlain 

 by the great mass of typical conglomerate. There is a local bed of red 

 shales in this conglomerate not far from the axis of the synclinal. The 

 basal red slates with red pebbly quartzites which underlie the conglom- 

 erate are exposed at the west end of the gap and they are underlain by 

 small amounts of gray flags. Along the road, a mile south of this locality 

 there is an exposure of the conglomerates very, near the gneiss. 



In the region northwest of Newfoundland the Bearfort mountain rap- 

 idly decreases in height, the sj^nclinal opens and rises, and the conglom- 

 erate has been eroded away. The red and gray quartzite beds and the 

 red slates cross the end of the mountain around the rim of the synclinal. 

 The red slates are well exposed on the south shore of the new reservoir at 

 Clinton falls, two miles northeast of Newfoundland, overlying the flag 

 series and the synclinal is clearly exhibited by them. 



The age of the Skunnemunk conglomerate is not definitely known. 

 It is suggested that it may represent the Oneonta horizon, for the deposi- 

 tion of the Oneonta formation in central New York was characterized by 

 an abrupt change to coarse sedimentation. Possibly the age is later than 

 this, and the formation may be equivalent to the coarse beds of Chemung 

 age in the southern Catskills, or it may be a purely local feature. 



Belhale Flags. — The hard, thin-],)edded sandstones, which contain De- 

 vonian plants on Skunnemunk mountain, extend southward through 

 Bellvale mountain and along the eastern side of Bearfort mountain 

 nearly to Newfoundland. They merge into dark-colored slates below,' 

 but the horizon of transition is a somewhat variable one. The greatest 

 development of the formation is along the eastern side of Bearfort moun- 

 tain, where the thickness is not less than 2,000 feet. In the eastern part 

 of Skunnemunk mountain the amount has been estimated by Smock at 

 1,300 feet, including the underlying slates, but it is somewhat greater 

 than this to the northward. The flags terminate northward in the 

 northern slope of Skunnemunk mountain southwest of Cornwall Station. 

 The rocks present some variation in color, hardness and thickness of 

 bedding, but the predominating character is a dark gray, hard, moder- 



