Hawkins — Notes on the Geology of Rhode Island. 447 



arkose, 14 thus proving it to be "pre-Carboniferous." 15 

 Similar granites are found at Mount Hope, in Bristol, 

 and at Common Fence Point, on the northern end of 

 Aquidneck Island. 



At three points along the southern Rhode Island coast 

 there are exposures of granite of a different and perhaps 

 later type. A very coarse reddish biotite granite with 

 white feldspars underlies Sakonnet Point, It shows 

 spots of dioritic appearance, inclusions, or due to differ- 

 entiation. It cuts chlorite schist and is cut by aplite and 

 minette. It becomes more gneissic eastward. Contact 

 relations with surrounding formations are not exposed. 

 A granite of closely similar appearance is extensively 

 exposed at Newport. 16 Again relations are concealed. 

 A similar state of affairs exists at the headland of Quo- 

 nochontaug, which is formed of a coarse red biotite 

 granite, cut by heavy pinkish pegmatite dikes. 



Emerson and Perry 17 favor "the early Carboniferous 

 age" of the East Greenwich granite group ; yet "there is 

 indication of a blending of the (granite porphyry) 

 breccia upward with the ordinary Carboniferous con- 

 glomerate." This is taken to "suggest the idea that 

 they are the result of an eruption of tuffaceous material 

 rather than the result of slow erosion on the surface of 

 the laccolith," the fragments seeming "to have been car- 

 ried along and to have been cemented by a small quantity 

 of the granite porphyry." However, "the recent dis- 

 cussions of Barrell, Mansfield, and others on the conti- 

 nental transportation of unaltered feldspathic material 

 in semiarid regions suggests another explanation of 

 the fresh granite pebbles in the conglomerate" (op. 

 cit.). "The conclusive evidence seems to be lacking" 

 (Foerste) 18 ; but "the succession of events becomes 

 simpler if we assume that the porphyries and micro- 

 granites of the series formed the surface of a rather 

 thinly covered batholith, which was just exposed by 

 erosion in early Carboniferous time." 17 The present 

 writer agrees with the latter statements. The contact 

 of the East Greenwich granite group with the adjacent 



14 Shaler, Woochvorth, and Foerste, op. cit., 233. 



15 Emerson and Perry, op. cit., 46. 



16 Shaler, Woodworth, and Foerste, op. cit., 316. 



17 Op. cit., 69. 



18 Shaler, Woodworth, and Foerste, op. cit. 



