184 GEOLOGY OF OLD HAMPSHIRE COUNTY. MASS. 



crumpled liguiform structure. The whole is often also largely contorted 

 and full of white quartz veins. It is of such fine grain that the separate 

 naica scales are just visible. 



It is very generally a "spangled schist," oval or elongate biotite crys- 

 tals being set transversely to the bedding, and over considerable area all 

 parallel to a common plane, which seems always to be the plane normal to 

 the direction of pressure at the time the crystals were de))0sited 



Garnet and staurolite are usually abundant, especially in the southern 

 half of the area. In Cummington they become rare, and north of this 

 town the staurolite disappears almost entirely, coiucidently with the disap- 

 pearance of the great granite masses. There is often an interlamination of 

 more and less sandy layers, and in this case the more sandy layers lose the 

 fine coiTugation described above, but retain the spangles of transverse mica. 



Toward the east, where the mica-schist is entangled in the great masses 

 of granite in Williamsburg and Westhampton, it largely loses the. fine reg- 

 ular coiTUgation in an extreme and irregular twisting and contortion, and it 

 becomes of much coarser grain and barren of all accessory minerals except 

 a few garnets. 



The cliffs just south of the locality for colored tourmaline on the old 

 Weeks farm in Groshen (now Barras farm) are composed of a typical black, 

 coarse, spangled, corrugated muscovite-schist. 



I have chosen Conway as the general type of this series because it was 

 there first studied by President Hitchcock, and because it is there most 

 calciferous and best shows the whole range of variety of the series. 



Through Russell, Blandford, Montgomery, and Huntington gray cya- 

 nite is a common constituent. In the next tier of towns, Worthington and 

 Chesterfield, it is not so common, but occurs in finer specimens of rich blue 

 color. It is here not so regularly disseminated in the rock as farther south, 

 but is in veins of coarse quartz, at times associated with apatite. 



In the same latitude, in Goshen and Williamsburg, zoisite is quite com- 

 mon, and zoisite, cyanite, and staurolite disappear from the continuation of 

 these beds north across Franklin County, parallel with the increase in the 

 amoimt of limestone, though bowlders of zoisite abound in Shelbume. 



As a quite exceptional occurrence a large area of the schist on the hill 

 north of Anson Johnson's mill, on the Worthington-Chesterfield line, and 

 not near any granite, is full of small black needles of tourmaline. 



