100 



red sandstone and shale formation of the northwestern flank, and 

 to the underlying slate, and the confornnable dip of all these rocks 

 towards the northwest, is well exhibited in that fine natural gorge 

 of the mountain, the Water Gap of the Delaware. Here, the en- 

 tire structure of the ridge is exposed, showing the gray sandstone 

 rising in bold grandeur from the water's edge to the crest of the 

 mountain, an elevation of about fourteen hundred and fifty feet. 

 The ridge preserves this height with a remarkably straight and 

 even summit for many miles, in both directions from the river. 

 This levelness and perfect straightness of the mountain top, the 

 regularity of its grand escarpment on the east, and the striking 

 uniformity in the general dip of its strata, suggests the remarkable 

 equality in the intensity and direction of that force from below, 

 which uplifted from their deep bed under the waves, this pon- 

 derous mass of rocks. 



Composition and Structure. — The gray sandstone formation of 

 the Kittatinny Mountain consists of a thick series of hard white 

 and whitish-gray siliceous rocks of various degrees of coarseness, 

 from that of a fine-grained pure sandstone to that of a quartzose 

 conglomerate of thickly set pebbles, averaging half an inch in 

 diameter; these several varieties are found interposed in frequent 

 alternations, though the fine-grained sandstones most abound in 

 the upper half of the stratum, while the conglomerates prevail 

 to rather greater amount in the lower division. In the vicinity of 

 the Lehigh river, in Pennsylvania, the main deposit consists of 

 pebbles, often of great size, which compose the lowest beds of 

 the formation, resting in immediate contact with the subjacent 

 slate. 



From the Susquehanna river to the district of the Lehigh and 

 Delaware, the formation would appear to augment progressively 

 in thickness and general coarseness of composition, being only 

 about four hundred feet thick near the first river, and almost two 

 thousand feet at the Lehigh; but advancing from the Water Gap 

 of the Delaware towards the Hudson, it again abates somewhat 

 in thickness, retaining, however, its full proportion of the white 

 quartzose conglomerates. 



Upon examining the composition of the rock, it will be found 

 to consist of rounded fragments in the condition of sand and fine 

 gravel, derived from the primary rocks lying southeast and east 



