INDEX. 279 



Dedham, breccia in, 80-81. 



Devonian? 273-275. 



Diabase, exotic, in Medford, Somerville, and Brookline, 22, 255-256. 



exfoliation of, 230, 248, 256. 

 Diorite, exotic, 101-104. 



argentiferous galena in, 103. 

 biotite in, 103. 

 distribution of, 104. 

 distinguisbed from syenite, 102. 

 relations to granite, 101-102. 



relations to stratified group, 101, 105, 106, 110, 112. 

 Dodge, W. W., conglomerate in Needbam, 250. 

 Norfolk County basin, 274. 

 relations of conglomerate and slate, 186. 

 slate in Newton, 253. 

 slate in Soutb Boston, 236. 

 slate in Weymouth, 206. 

 Dorchester, synclinal in, 226. 



Elvanite, in Blue Hills, 89-91. 

 on Lowell's Island, 73. 

 in Needham, 79. 

 in West Roxbury, 82. 

 relations to granite, 89-91. 

 See Petrosilex. 

 Eozoic, subdivisions of, in Eastern Mass., 13. 

 Eozoic formations, chronologically distinct, 12. 



general relations of in Eastern Mass., 161-163. 

 See Huronian, Montalban, etc. 

 Eozoon canadense, in Huronian limestone, 114. 



in Montalban limestone, 125, 139. 

 in Newbury, 25. 

 range in time, 140. 

 Essex County, N. Y., analysis of labradorite from, 17. 



Felsite, analyses of, 72, 75, 78, 89. 



definition of, 46. 



at Dungeon Rock in Lynn, 75. 



on Marblehead Rock, 72. 



passing into diorite, 78. 



physical characters of, 93. 



pinite in, 89. 



See Petrosilex. 

 Forest Hills Cemetery, escarpment in, 227. 

 Franklin, Mass., Naugus Head series in, 23. 



• 



Gallop Island, rocks of, 223. 

 George's Island, 216. 

 Gneiss, Montalban, 135-136. 



on Cape Cod, 136. 



