366 STRATIGRAPHICAL GEOLOGY. 



Observatory hill, from 32°-4i° N. 50° W. The western border of this 

 band touches Norwich about a quarter of a mile above the depot. Along 

 Connecticut river the rock appears abundantly below the Ledyard bridge, 

 as at Negro island, Granny's island, and at both the upper (Olcott's) and 

 the lower falls. The hill east of these localities shows the same rock rising 

 above the alluvium. (See plate opposite p. 302, vol. i.) At the upper falls, 

 east side, the dip is 52° N. 80° W. On the west side of the river the dip 

 is 44° N. 85° W., and at the railroad nearly 46° N. 85° W. This is at the 

 extreme western edge of the formation, where it comes in contact with 

 the Huronian grits. The positions at the lower falls are indicated upon 

 Fig. 59. Below the lower falls the ledges are frequent as far as the rail- 

 road bridge by White River Junction. A mile or so south of the junc- 

 tion the hornblende dips 65° W., nearly in contact with the Huronian. 

 Opposite this point is a small hummock of the same rock, rising out of 

 the meadow south of Mascomy river. The formation now increases in 

 width very much, and lies entirely on the east side of the Connecticut. 

 West of S. Waterman's a large hill is made of hornblende, dipping 50° S. 

 65° W. Blood's or Hinckley brook cuts through this hill near the line 

 of Lebanon and Plainfield, making a deep, narrow gorge seventy-five feet 

 deep for a distance of half a mile. In this chasm the dip is 50° S. 70° 

 W. In this neighborhood there are several ledges dipping in the oppo- 

 site direction, so that two foldings of the strata are inferred. They may 

 not be of large extent. The noticeable change in the strike is due to the 

 disappearance of the Bethlehem gneiss to the east, as the hornblende 

 rock is forced to conform in disposition to the older area. In the north- 

 west part of Plainfield this ridge is continuous in Governor's and Black 

 hills. Beyond, our observations are scanty, but we seem to be authorized 

 to affirm that the hornblende rock ceases to crop out on the surface in 

 the neighborhood of Mud pond. Ledges of it are marked adjacent to 

 Connecticut river, in the north-west corner of the town, towards Wil- 

 lard's ledge, and by Governor's hill. Near W. H. Daniels's the dip is 

 north-westerly, and the rock is somewhat gneissic. 



The range appearing on Craft's hill crosses the Mascomy river with 

 the railroad, dipping 42° N. 63° W. We arc unable to trace this band 

 to a direct connection with the main mass farther south. The ledges by 

 S. Woods's, extending half a mile south to the school-house and dipping 



