90 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



trace of olivine that has been found west of the river, except the Middlefield 

 pseudomorphs mentioned above. 



A bed of pegmatite a rod wide separates the serpentine from schist, 

 which continues up the hill 412 feet to the Griswold house. 



THE GRANVILLE AND RUSSELL ENSTATITE- SERPENTINES. 



From the section north of Borden Brook, in the south of Blandford, 

 where the hornblendic complex is made up of several amphibolite beds 

 alternating with beds of sericite-schist, the series continues due south into 

 Grranville, and is for a short distance inteiTupted by pegmatite, but attains 

 in Liberty Hill a thickness of 1,237 feet of clear, black amphibolite without 

 interlaminated mica beds. It curves east and then west and retains this 

 great width for a mile, and continues southwest as two bands of amphibo- 

 lite, each about 15 feet wide. These soon run out southward, and no trace 

 of them could be found in the well-exposed bluffs east of West Hartland. 

 Where it bends most easterly it contains the heavy bed of steatite (bed 

 No. 13) a mile southwest of West Granville, at the bottom of the bluff east 

 of E. Williams's house. Here some work has been done upon a deposit 

 of steatite, which has been derived from a bed of fine, radiated tremolite; 

 it still retains the structure, and part of it the hardness, of hornblende, and 

 therefore the bed is not a promising one to work. Many bowlders of 

 the black enstatite-serpentine occur near Mr. Williams's house, which must 

 come from another bed of the rock near at hand, as the two rocks seem to 

 be connected genetically, since the tremolite is exactly like that found 

 with the serpentine of the next locality. Just after crossing the State line 

 and Hubbard Brook the amphibolite band cames a bed of black enstatite- 

 serpentine (bed No. 14), of which about 5 or 6 feet is exposed. 



On the southeast flank of Liberty Hill, in West Granville, a branch of the 

 amphibolite separates from the main bed, as mentioned above, and, bending 

 round sharply, runs north with much diminished thickness, not exceeding 

 6 feet, to a point west of East Granville, where it bends north again and 

 carries the remarkable bed of enstatite-serpentine (bed No. 15) which occurs 

 in a densely wooded swamp 100 rods east of the house of J. Downey. A 

 ridge 20 feet wide and rising 24 feet is exposed for a considerable distance, 

 and, as usual, the serpentine is associated with amphibolite. It is a black 

 serpentine, made up of crystals an inch square on the end and more than 2 



