466 Hawkins — Notes on the Geology of Rhode Island. 



limestone goes on as a natural result of burial in the zone 

 of anamorphism, and is not dependent upon introduction 

 of siliceous emanations from invading granites. Talc 

 and serpentine (bowenite), occurring locally in the lime- 

 stone, must have been derived from hydration of the 

 silicates by circulating waters ; the bowenite may possi- 

 bly represent included layers or fragments of material 

 from the adjacent schist. Analyses of the limestone 

 have been published (Emerson and Perry, op. cit, 17-18). 

 The additional analyses which follow (Table III) may 

 serve to show the relations of the granites, pseudo- 

 diorites, and green schists, where they are found 

 together. The details appear to be somewhat as 

 follows : — 



The granite from the east slope of Neutaconkanut Hill 

 is found to show the following gains when compared with 

 the normal Milford granite at Hughesdale: — 



A1 2 0, 4-09% 



Fe 2 3 1-90 



FeO -72 



MgO -57 



CaO 410 



11-38% 



This sum indicates that, if the increase in basicity be due, 

 as it apparently is, to assimilation of the basic rock, 

 11-38% of the granite at a distance of 20 feet from the 

 contact is assimilated schist. If this be true at 20 feet 

 from the contact, it is reasonable to suppose the same 

 conditions to continue the same on the average from the 

 contact to a point at a distance of 25 feet from it. Then 

 in this 25-foot band of granite there is 11-38% of schist 

 intermixed, i. e., 11-38% of the amounts of elements 

 gained by the granite, present in the schist analysis, is 

 present in every like amount of the granite, to a distance 

 of 25 feet ; or the full amounts of elements present in the 

 schist analysis are present in every 11-38% of 25 feet, or 

 2-84 feet, of the granite ; this represents the amount of 

 schist (2-84 feet) that has been assimilated. For the 

 Neutaconkanut Hill locality this much at least is indi- 

 cated by analysis, although possibly more schist was 

 assimilated in portions of the granite nearer to, and less 

 in those farther away from, the contact. These zones are 

 not shown on account of lack of exposures. To distances 



