18 



stone ; but from the latter point to where they strike the Dela- 

 ware, they are overlaid, throughout the chief part of their course, 

 by the calcareous conglomerate, which caps the middle secondary 

 series. 



The northwestern margin of this same chain of the gneiss, is 

 marked by the edge of the Musconetcong Valley, and sometimes 

 by the border of that stream itself, along the entire distance be- 

 tween its outlet at the Delaware and the head of the valley, near 

 the old Andover Forge, the primary strata everywhere descend- 

 ing beneath the older secondary limestone. From the old Ando- 

 ver Forge, it follows nearly the brink of Musconetcong creek 

 by Stanhope to Brookland, at the outlet of the Hopatcong Pond, 

 being generally, except at Stanhope, in contact with the limestone. 

 It there folds round the base of a hill west of the Pond, which it 

 pursues, passing a little east of Columbia Forge and the villages 

 of Sparta, Ogdensburg, Hamburg, and Vernon, to New Milford, 

 at the State line. In all this part of its somewhat undulating 

 course, the gneiss dips beneath the overlapping edge of the older 

 secondary limestone. 



The mountain belt of which the boundary has here been traced, 

 consists essentially of a single uninterrupted belt of axes of 

 elevation, giving to it a general anticlinal structure. It receives, 

 nevertheless, several distinct appellations, applied to difTerent por- 

 tions of it. Between the sources of the Pequannock and the deep 

 transverse gorge which almost intersects the chain at Drakesville, 

 it takes the title of the Hamburg or Wallkill Mountain. From 

 the cross valley above mentioned to that of Spruce Run, it bears 

 the name of Schooley's Mountain, while between the latter limit 

 and the Delaware river, it is called the Musconetcong Mountain. 



To the northwest of the great continuous belt of primary hills, 

 whose boundaries have just been traced, there rises a chain of 

 rather less elevated scattered ridges, M-hich occupy insulated 

 tracts in what, if we take a comprehensive view of the topogra- 

 phy of the region, ought to be regarded as the southeastern por- 

 tion of the Kittatinny Valley. These hills are surrounded on all 

 sides by the older secondary limestone of that valley, through 

 which at least some of them seem to have been protruded sub- 

 sequently to the period of deposition of the limestone over the 

 gneiss. Though they do not constitute a strictly connected range 



