GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 



331 



Fitch hill, in consequence of the transverse course of the latter, it is 

 wanting, as shown in Fig. 40. To the south-west there is another out- 

 crop of this older range, and the Helderberg is cut off by it ; but the fos- 

 siliferous seam again covers it when the low ground is reached, and the 

 hard rock is seen no more. 



Furthermore, the contact between the Helderberg and the diabase or 

 chloritic strata on Fitch hill is not a direct succession or interstratifica- 

 tion, since there has been a sliding of one rock over the other. The 

 removal of the turf revealed a slickenside between them. As expressed 

 by Prof. W. B. Rogers, who examined the locality 

 with us a few days later, it "looks as if the lime- 9 

 stone had backed up on to the green rock." These :^ I' 

 facts are mentioned to show our reasons for be- | |. 

 lieving that the Helderberg rocks on Fitch hill and i " 

 the neighborhood overlie the Lisbon group uncon- « | 

 formably. "^ ^ 



The order of the rocks from Fitch's house to the I f 

 very summit of the hill is well shown in Fig. 40. ^;: 

 What I have called the top of the hill thus far, sig- f ? 

 nifies the highest part of the cleared land. This ^ ^. 

 section reaches the very summit, which is wooded. 

 Above the Lisbon series come about fifty feet of 

 Lower Helderberg limestone, holding the chain 

 coral, Pcntavienis, and a gasteropod, with the oth- 

 ers mentioned by Mr, Billings. This is followed by 

 forty or fifty feet of coralline slate ; thirty or forty 

 feet of friable conglomerate, white, when weath- 

 ered, like the Oriskany sandstone of New York, 

 the quartz pebbles being of the size of kernels of Indian com. Next is a 

 bluish, compact feldspar, somewhat resembling siliceous limestone; then 

 follows considerable tough, massive hornblende rock, with no signs of 

 stratification, which, with the felsite, is supposed to be a repetition of 

 the underlying Huronian. On the very apex of the hill is a sandstone 

 weathering white, but gray in the interior. It dips apparently fifty de- 

 grees east of north. The section is about half a mile long. 



Following the limestone south-west, perhaps a fourth of a mile, we 





n r 

 3 



