180 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



the heavy bed of hornblende-schist is a hayer of thin-bedded, soft, dark, 

 crumbly schist, made vip mostly of muscovite, and almost wholly barren, 

 showing rarely a large, shapeless garnet. This is 40 rods wide, and is per- 

 haps best assigned to the sericite-schist, though on the map it is colored 

 with the upper bed. The change above is abrupt into the garnet- and 

 staurolite-bearing flags. 



The doubtful border layer mentioned above continues north across 

 Cummington; and on the road to West Cummington, south of Deer Hill, the 

 dolomitic fasciculite-schist (Hawley series) appears at L. Packard's, with 

 amphibolite on the east of it, and just east of this amphibolite is a black, 

 fine-grained, graphitic schist, pimpled with garnets, which is the base of the 

 Goshen schist and the continuation of the doubtful layer mentioned above; 

 and directly east of this again is a thin amphibolite layer, which is a repeti- 

 tion of the Hawley beds, followed immediately by the light-gray Goshen 

 flags. Across Hawlej'^ and Plainfield the junction is nowhere well exposed. 



At the first cut east of the Charlemont railroad station the same gra- 

 phitic, thin-fissile slate occm-s just above and to the east of the highest 

 hornblendic bed of the Hawley schist, and is followed above by the Goshen 

 flags, with the intervention here also of a bed of amphibolite, and this curious 

 boundary continues diagonally across Heath from the mills west of the 

 center to the northeast corner. An important change takes place here 

 which indicates the unconformity between the two formations. The bed of 

 porphyritic amphibolite near the top of the sericite-schist is continuous clear 

 across the town of Heath, and a little above this the light-gray, quartzy 

 fasciculite-sericite-schist (Hawley) comes in on the east with gradually 

 increasing width and is succeeded a little farther east by a very plum- 

 baginous, friable slate, in which I searched a long time for fossils. This 

 bed has been dug for plumbago near J. D. Tinkham's, and it is well 

 exposed at J. Loveridge's, in the northeast corner of the town. It grows 

 wider as it goes north, and develops into well-characterized Goshen flags, 

 and is plainly an outlier of these rocks embedded in the Hawley schists. 



East of this bed the band of porphyritic amphibolite which was men- 

 tioned above in the Cummington and the Charlemont section widens and 

 becomes across the whole of Heath 820 feet wide. This structure is well 

 brought out upon the geological map and the sections accompanying it. 

 (See map, PI. XXXIV.) 



