Hawkins — Notes on the Geology of Rhode Island. 443 



It should be noted, however, that similar pegmatites also 

 cut the Sterling as freely as they do the sediments (op. 

 cit.). Such intrusions of both the granite and its border- 

 ing invaded rocks does not destroy the possibility that the 

 pegmatites may be a late phase following the intrusion 

 of the main portion of the Sterling batholith. The peg- 

 matites, however, seem quite free from gneissic shear 

 effects similar to those in the Sterling. Intrusion after 

 solidification of the Sterling batholith would naturally 

 appear in strongest development along its border, 

 especially if there were some faulting along that border, 

 as there may have been in the vicinity of Tower Hill. 

 These pegmatite and granite dikes, as suggested by Pro- 

 fessor C. W. Brown, may well be more easily supposed to 

 be contemporaneous with the "Westerly granite intrusion 

 (post-Sterling) than with the Sterling granite gneiss 

 itself ; then, too, a small dike of granite similar in type to 

 the Westerly granite, to which the writer's attention was 

 called by Professor Brown, intrudes the Carboniferous 

 sediments at Hamilton, just south of the point where the 

 trolley track intersects the highway. If actually con- 

 nected with the Westerly intrusive granite sills, this dike 

 would establish the post-Carboniferous age of the West- 

 erly granite. Additional and seemingly conclusive evi- 

 dence of the pre- Carboniferous age of the Sterling gran- 

 ite gneiss is furnished by the following field evidence : — ■ 

 A few years ago the Natural Ee sources Survey of 

 Rhode Island (with which the writer was at that time 

 working in the field), in the course of work in the west- 

 ern part of the State, made careful records, under the 

 direction of the Superintendent, Professor Brown, of 

 dips and strikes of gneissic foliation of the various out- 

 crops of granite gneisses and associated rocks of the area. 

 In spite of scarcity of good outcrops, and the obscurity of 

 data caused by the extreme metamorphism, many good 

 readings were made and recorded. These the writer, in 

 the course of this present work, subsequently plotted, in 

 addition to other, personal, observations in the north- 

 western portion of the State. The Sterling granite 

 gneiss is a rock whose gneissic character is pronounced 

 and widespread, in Rhode Island as well as in eastern 

 Connecticut (a point not noted by Loughlin), giving it a 

 banded structure, which, whether due to flowage or 

 regional metamorphism, or both, is definitely connected 



