330 STRATIGRAPHICAL GEOLOGY. 



crops of limestone, some of them containing coral masses. A slaty mass 

 with no cleavage is mixed with it. The limestone near the first house on 

 the west side of Parker brook is bluish, and was at first supposed to be- 

 long to the Lisbon series, as it is not fossiliferous. It has been excavated 

 for a kiln in years gone by. Recent researches indicate that the whole 

 of this hillside, perhaps into Lisbon, is of Helderberg age. The strata 

 have somewhat of a zigzag arrangement, which need not be described in 

 detail. 



Directly beyond the brick-kiln we find the chloritic rock in its per- 

 fection, dipping in the same direction with that already noted, but at a 

 steeper angle, and the range is only thirty rods wide. At a turn in the 

 road, slate of less width, seemingly vertical, appears ; and we discovered 

 imbedded in it two feet thickness of compact crinoidal limestone. This 

 identifies the slate with the deposit upon Fitch hill, a quarter of a mile 

 to the south-west, where the Pentameras is found. The mingled slate 

 and limestone extend up the hill, and then across the ridge. 



The chloritic rock reappears on the section at a fork in the road, and 

 continues uninterruptedly for three eighths of a mile, dipping 75°-8o° 

 north-westerly. This would give a thickness of about 1900 feet of strata. 

 This is undoubtedly continuous to the west end of Fig. 36 in one direc- 

 tion, and to the ledge under the slate quarry in the other, a distance of 

 about three miles. 



The Fitch Hill locahty was discovered September 22, 1873. Mr. J. H. 

 Huntington and A. S. Bachelor, of Littleton, and myself composed the 

 exploring party; and Mr. Huntington first detected the presence of the 

 Pentamerus. Our attention was called to the spot by Mr. A. R. Burton, 

 of the village, who had seen limestone there. It is about fifty rods south- 

 erly from E. Fitch's house, in an open pasture, near the forest and above 

 an orchard. The first rock seen above Mr. Fitch's is the chloritic feld- 

 spathic layer of the Lisbon group, running N. 55°-6o° E., and containing 

 a layer of white quartz. In the pasture the strike changes to nearly east 

 and west; and this fact is made certain by the position there of the white 

 quartz, which curves with the Lisbon rock, but may be a little nearer the 

 Helderberg after the bend is passed than before. This is confirmed by 

 examining the rocks east of the Helderberg range. On Fig. 39, below, 

 there are thirty rods of chloritic rock east of the slate range, but on 



