GEOLOGY OF TH-^ CONNECTICUT VALLEY DISTRICT. 283 



and about one hundred and twenty-five feet in width, having a lenticular 

 shape, and a north-westerly dip. The quartz resembles that occurring in 

 the Atlantic gneiss, breaking up into rectangular pieces, and somewhat 

 reticulated by small quartz veins. It forms a prominent feature upon the 

 north side of the road. The next two are smaller patches, on both sides 

 of the road near J. Titus's. The more southern runs into one of large size 

 upon the northern slope of the hill, that is very conspicuous as seen from 

 the road between Lisbon and the Dodge gold mine. The other exposure 

 is about a thousand feet south-west from J. Corey's house, on the last 

 road mentioned. It may be three hundred feet long and one hundred 

 wide. The clay slate butts against this quartz boss, having a dip of 43° 

 N. 20° W., and a sliding between the rocks is obvious. I cannot say that 

 this quartz is certainly represented beyond these limits; but suggest it 

 may be the equivalent of the large mass alluded to above, adjacent to 

 the southern end of the slate in Bath, and the beds upon Fitch hill in 

 Littleton. 



This range of lenticular quartz bosses furnishes us with an excellent 

 example of unconformability between the Lisbon schists and the clay 

 slates. The first ledge lies on the line between the Lisbon and Lyman 

 groups, and is removed entirely from all connection with any areas of 

 slate, the nearest one being 1300 feet to the south-west, on the line of 

 strike. The next exposures, at Titus's, are 11 50 feet south-east from the 

 principal range of slate lying to the north-west of the range just men- 

 tioned, if it were prolonged. Near Corey's house the eastern border of 

 the slate — the direct continuation of that north-west of Titus's — is situ- 

 ated five hundred and thirty feet east of the quartz. We have therefore 

 a strip of quartz crossed transversely by the slate at an angle of seven- 

 teen degrees. The length of the quartz between the points measured is 

 nine hundred feet, and the sum of the easting and westing is 1680 feet. 

 In other words, the eastern border of the slate, which was 11 50 feet 

 north-west of the quartz at Titus's, crosses it, and lies 1680 feet farther 

 to the south-east, opposite Corey's, than it would were there no uncon- 

 formity. Evidence is afforded of a fault near Titus's ; but this does not 

 seriously affect the fact of unconformability, which is corroborated by the 

 common relations of the two formations explained in detail elsewhere. 



There are other ledges along the Ammonoosuc river before coming to 



