16 



owe their elevation. The next continuous zone of prinnary strata, is 

 one of far more extensive area. It is included between the general 

 northwest boundary of the middle secondary rocks, on the one 

 hand, and on the other, the long unbroken valley, which com- 

 mences at Clinton, and extends thence along the south branch 

 of the Raritan to its source at Drakeville, and by Green Pond, 

 Macapin Pond, and Long Pond to Dutch Hollow, in the State 

 of New York. Between these limits its range is uninterrupted 

 from near Clinton to the State line, or indeed to the Hudson. 

 To trace this belt of gneiss rocks more exactly, we follow them 

 from the point where the Ramapo river crosses the State line, 

 along the northwestern border of the Ramapo Valley to Pompton, 

 a little north of Ryerson's. Throughout this distance they are 

 overlaid by the middle secondary, red shale, and sandstone 

 group. In the neighbourhood of Ryerson's, a calcareous conglo- 

 merate, which when present is the uppermost stratum of that 

 group, lies nearest to the gneiss ; the immediate boundary of 

 which, however, is very commonly concealed along the base of 

 the hills, by a deep covering of diluvial gravel. From Pompton, 

 in contact for a part of the space with the diluvial matter which 

 composes the substratum of the Pompton Plains, the gneiss rocks 

 take their course along the foot of the Pompton Mountain by Mont- 

 viile and Boonton Falls, and thence along the base of the Trow- 

 bridge Mountain to near Mendham. 



As far as this latter point, the overlapping rocks are the upper 

 beds of the middle secondary formation. In the Mendham Valley, 

 the gneiss comes in contact, for a distance of a few miles, as far 

 as Pepack, with the blue limestone of the Appalachian or lower 

 secondary series. From Pepack the formation extends still to 

 the southwest, passing about a mile to the north of New German- 

 town, and thence in a more westward direction to a point nearly 

 north from Lebanon and two miles northeast of Clinton, where it 

 meets the limestone of the valley of the South Branch. Between 

 Pepack and a point nearly north from Lebanon, the gneiss is, wdth 

 some few interruptions, in contact with the calcareous conglo- 

 merate, the uppermost stratum of the middle secondary rocks. 

 Sweeping round to the north, and afterwards to the northeast, 

 the margin of the gneiss thence pursues the southeastern side of 

 the valley of the South Branch, or German Valley, in contact 



