52 The American Geologist. January, looo 
occur mostly in parallel north-and-south bands running entirely 
across New England. 
The crystalline rocks succeed each other in ascending order as 
follows: (i) the Washington graphitic gneiss of pre-Cambrian 
(Algonkian) age; (2) the Becket Cambrian gneiss, locally at base a 
conglomerate, found abundantly west of this area wrapping around 
pre-Camhrian nuclei, and showing a small development within the 
area on ilic west, while east of the Connecticut it is represented in 
force by the Monson gneiss; (3) the Hoosac and Rowe sericite- 
schists separated by the Chester amphibolyte from Savoy and Haw- 
ley chlorite-schists above, all of Lower Silurian age; (4) the Upper 
Silurian Goschen and Conway schists graduating upward into the 
Leyden argill3'te; (5) the Bernardston series of Devonian age, in- 
cluding gneiss, limestone, cjuartzyte, schist and amphibolyte. Uncon- 
formity exists between all of these series. The age of the Bernardston 
series is dertermined by fossils, that of the three lower series by trac- 
ing them west into Berkshire county, where fossils are found. The 
succession above is that west of the Connecticut. The crystalline 
rocks east of the river are not continuous with those west, but the two 
are parallelled on stratigraphic and petrographic grounds. Some of 
the upper schists are lacking to the east and on going still further 
east into Worcester county the series becomes still simpler. A very 
interesting section of the report is that dealing with the Chester am- 
phibolyte and the associated lenticular masses of serpentine and beds 
of emery. The serpentine is believed to represent an original- dolo- 
mitic limestone, the amphibolyte an impure argillaceous limestone and 
the emery and magnetite deposits may have been formed by a re- 
placement of a portion of the limestone in a manner analogous to its 
replacement by limonite at the surface of the Stockbridge limestone in 
Berkshire county. The details of the paragenesis are given for the 
serpentine and emery. Amphibolytes also occur in the Conway schists 
and in the Bernardston series and these are considered to have had a 
similar origin to that of the Chester rock. Some of the amphibolytes 
are referred to original igneous rocks. 
The crystalline rocks in the western part of the area form a series 
of close folds often overturned to the west, and but seldom faulted. 
Passing eastward the rocks become more faulted, are abundantly cut 
by igneous rocks and show increasing metamorphism. The most 
abundant of these erupt ives cutting the metamorphic rocks are gran- 
ite and tonalyte of late Devonian or Carboniferous age, which occur 
in their largest development immediately on the borders of the 
Triassic. 
These eruptivcs vary from very basic (noryte and corllandyte) to 
acidic (ni.uscovite-biotite-granite and pegmatyte), but granite and 
tonalyte alone occur in great abundance. These occur within a square. 
twenty-five miles on a side, with Northhampton as its center. The 
central portion of this area is covered by Triassic sandstone. Toward 
the center of this square occur large areas of muscovite-biotite-granite 
