INDEX. 285 



Primordial seeies, relations to granite, 192, 193, 206, 207, 209-212, 260. 

 relations to petrosilex, 263-264. 

 relations to Shawmut group, 197, 198, 204, 205, 209, 220, 232, 247- 



248, 264, 268. 

 sections of, 201-206, 210-211, 222-223, 227-228, 238-239. 

 thickness of, 265-266. 

 See Conglomerate, Limestone and Slate. 

 Puddiugstone. See Conglomerate! 

 Pumpelly, Raphael, on the brecciated petrosilex of Pilot Knob, Missouri, 50. 



Quarantine Rocks, slate on, 214-215. 

 Quartzite, Huronian, 105-112. 



relations to petrosilex, 105-106. 

 Quartz - porphyry. See Elvanite. 



Raccoon Island, slate on, 209. 



Rainsford Island, slate on, 214-215. 



Reading, Naugus Head series in, 23. 



Rhode Island, geology of, 128, 146-147. 



River Parker, basin of, 267-268. 



Rogers, W. B., slate on Governor's Island, 236. 



" Saugus Jasper," analysis of, 76. 



Shaler, N. S., Boston and Narragansett basins, 181-182. 

 Quincy granite, 36. 



slate at Chestnut-Hill Reservoir, 237-238, 242. 

 thickness of conglomerate and slate, 265-266. 

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

 Shawmut group, 163-180. 



conditions of the deposition of, 164. 

 general relations of, 177-180. 

 relations to Gulf of Maine, 164-165. 

 relations to Huronian, 47-55, 164, 177-178. 

 relations to Primordial system, 164-165. 

 relations of the breccia and amygdaloid of, 165. 



See Conglomerate, Petrosilex, Primordial system. Slate, Breccia, and 

 Amygdaloid. 

 Slate, Primordial, alteration of, 193-194, 197, 208, 247-248, 261. 

 amygdulos in, 192-194, 195, 262.. 

 cleavage of, 191, 192-193, 205, 209, 214-215, 221, 222, 238, 244, 



246, 254. 

 colors of, 191. 



composition of water from, 236-237. 

 contortions of, 214-215, 218, 241, 246, 247. 

 dykes in, 248,250, 255-258, 259, 261. 

 faults in, 258, 263, 265-266. 

 ferruginous, 251-252, 268. 

 in Hull, 201, 213. 

 jointing of, 191, 204, 214. 

 limestone in, 193, 195, 262. 

 minerals in, 193. 



