Lyman.] doO [Sept. 6, 



judgment, by Mr. E. B. Harden, formerly of the State Geological Survey, 

 Assistant Geologist and Topographer and in charge of the Headquarters, 

 Office and of Illustrations for the Reports. While Prof. Lewis's sketch 

 gives the confused appearance of the numerous cleavage planes as looked at 

 in a direction at right angles with the railroad, the photographs are views 

 in line with the northwesterly strike of the rocks, and show more or less 

 distinctly the dips and the bedding. For the rocks are clearly in fact not 

 confusedly broken fault rock, but simply dark gray and dark red hard 

 shales that are folded in basins and saddles with somewhat steep dips 

 (fifty to seventy degrees) ; such shales as occur extensively through 

 Bucks and Montgomery counties, and notably near the Gwynedd and 

 Phffinixville tunnels, as well as here and there along the banks of the 

 Neshaminy for a dozen miles below Chalfont. 



4. The right-hand edge of the eastern photograph (Plate xi), taken at 

 about one hundred and twenty-five yards east of the bridge over the west- 

 i rn end of the cut and about five yards south of the centre of the railroad, 

 shows very distinctly a dip of about fifty degrees southwesterly (south about 

 sixtj-^-three degrees west, true meridian). About the middle ground of the 

 view, against the tall post with a slender horizontal pole as a signal of danger 

 from the bridge to brakemen standing on height cars, the edges of the rock 

 beds are to be seen with a southwesterly dip of about seventy degrees, 

 that continues almost uniform westward and is sixty-five degrees, south 

 about forty eight degrees west, near the western end of the cut, towards 

 the bridge. That dip is also indicated in the more distant parts of the 

 picture by the course of the small hollows and gullies that descend from 

 the top of the cutting. 



5. These western dips are more distinctly seen, on a larger scale, in the 

 second photograph (Plate xii), taken at about twenty-six yards east of the 

 bridge and about eight feet south of the centre of the railroad, looking in the 

 same northwesterly direction along the strike. The layer, for example, 

 some fifteen iuclies thick, that comes to tiie level of the railroad in the 

 picture directly below the toot of the telegrai)h pole shows the dip un- 

 mistakably. Another layer about two feet to the east of that one is also 

 pretty clearly distinguished in the picture ; and the edge of another 

 parallel layer is to be seen about two inches, in the picture, to the west 

 of the first-mentioned layer. Besides that, the parallel edges of several 

 less striking layers, that can be perceived even in the photograph, cor- 

 roborate what is still more unquestionable on the ground, the uniform 

 southwesterly dip throughout the field of the western photograph. Prof, 

 Lewis's sketch apparently covered a portion of this field. 



6. The steep southwesterly dips, then, are plain through most of the 

 space covered bj"- the two photographs. On the ground, they are more- 

 over confirmed by the correspondence of small hollows occasioned by 

 softer layers on the two sides of the railroad, as readily observed by Mr. 

 Harden. The dips are still more easily recognized on the ground for 

 some distance east of the eastern photograph. Likewise, about fifty feet 



