GEOLOGY OF TIiE CONNECTICUT VALLEY DISTRICT, 445 



1858, I noted a quartzite dipping 60° N. W.; and in 1874 I observed a 

 ledge, presumably the same, standing vertically. Earth covers the imme- 

 diate junction of the quartzite and limestone; but as the latter dips ap- 

 parently beneath it, though at a small angle, it is so represented upon the 

 section. Yet the higher dips of the quartzite so near the limestones on 

 both sides may warrant one in suspecting the possibility of some irregu- 

 larity which should change our views of the relative ages of the rocks. 

 The limestone may be twenty-five or thirty feet thick, the place being 

 shown at No. 94. It abounds with fragments of crinoidal stems often 

 an inch across ; one end is frequently larger than the other. I have, also, 

 specimens of coral from it, quite obscure, which have never been sub- 

 mitted to a paleontologist. From the decomposition of the limestone a 

 considerable limonite has been formed, which was once manufactured into 

 pig iron. The limestone consists of carbonate of lime, 98.38; peroxide 

 of iron, 0.62; silica, i .00:= 1 00.00. 



A short distance west of the limestone occurs a brecciated rock, com- 

 posed of fragments of quartz and slate, dipping apparently 25° W. This 

 is succeeded by a dark-colored quartzite having the same position. This 

 is followed by quartzite of the usual variety seen to the east, with a dip 

 rather more southerly than that. The length of the section, protracted 

 sufficiently to include the westerly band of quartzite, is eighty rods. 



The observations from which our figure is constructed are mainly 

 those taken by my father in 1857 and by myself in 1858, and published 

 in the Vermont report. Prof. Dana has published a somewhat similar 

 figure in his sketch, to be mentioned presently. I do not speak of two 

 narrow argillaceous seams adjacent to the limestone, mentioned in 1858, 

 as they did not seem prominent in any later visits. I have examined 

 the section several times since 1858, once in company with Prof. Dana. 

 Some further remarks about this limestone, in its relations to the adjoin- 

 ing strata, will be appropriate after alluding to the opinions of my prede- 

 cessors. 



Later Rocks. 



The map shows an extension of the Triassic sandstone up the valley 

 of P^all river, reaching nearly to the limestone quarry. The slates have 

 probably been excavated across their edges transversely to form the basin 



