450 Loughlin — Intrusive Granites and Associated 



cent of the abundant bowlders in these three miles, and in fact 

 along the whole traverse, are of the normal gneissoid Sterling 

 granite, and it is the writer's experience that the majority of 

 bowlders in southern New England are of strictly local origin. 

 The granite therefore is believed to be continuous from the 

 Connecticut boundary to the edge of the Narragansett Basin, 

 1-J miles west of Wickford Junction, but the relations there 

 between the granite and the rocks of the Basin are concealed 

 by drift. 



The eastern part of this traverse overlaps a small part of the 

 area mapped by Emerson and Perry as a southward continua- 

 tion of the pre-Cambrian Northbridge gneiss of Massachusetts. 

 The thorough concealment of all contact relations renders it 

 impossible at this point to choose between the conclusion of the 

 authors cited and that of the writer. Evidence supporting 

 the writer's views will be presented in the description of the 

 Kingstown area. 



Evidence along the southern traverse is not quite so incon- 

 clusive as that just presented. The granite outcrops are all of 

 the Sterling types, chiefly the normal and to some extent the 

 porphyritic. Two small dikes of the Westerly type were 

 noted ; one a mile south of Plamiield, the other on the summit 

 of Shumunkanug Hill. No outcrops were found along the 

 eastern six miles of the traverse, but here again practically all 

 the bowlders are of the Sterling granite. 



Exposed inclusions of the metamorphic sediments are very 

 scarce and only one deserves mention. This one lies in the road 

 on the hill a mile west of Worden's Pond (see map, fig. 1). 

 Its texture is pseudo-porphyritic with flattened, lens-shaped 

 pebbles of quartz-schist, but the matrix is identical in color 

 and texture with the quartz-biotite schist exposed in southeast- 

 ern Connecticut and at Westerly. It is also similar to the 

 most severely metamorphosed conglomerate in the Kingstown 

 area. It is cut by a narrow pegmatite dike of the Sterling 

 (or Westerly) type. This evidence though limited proves that 

 the age relations found in Connecticut and at Westerly exist as 

 far east as Worden's Pond. 



The Kingstown Area. 



The limits of the Kingstown area are shown in fig. 2. It 

 includes the west boundary of the Narragansett Basin sedi- 

 ments from Hamilton southward, and has yielded decisive evi- 

 dence for determining the relative ages of the rocks in question. 

 The area was studied and mapped in detail by Messrs. Y. S. 

 Bonillas and Y. M. Frey under the writer's direction.* The 



*MS. thesis No. 340, 1908, Min. Dept. Mass. Inst. Tech., Boston, Mass. 



