Dodge.] 414 [February 3, 



with high dip, along the north side of the river toward Plympton- 

 ville. On the east side of the river, on the north side of Water 

 Street? under the bridge, there is some very hard reddish sandstone 

 dipping south-east, and with it much intrusive quartz. On the same 

 side of the street, on the shore of the pond, there are ledges of pud- 

 ding-stone. 



A mile south-east of the south-east corner of Medfield, I noticed 

 boulders of conglomerate in walls on the north side of Powder House 

 Hill, in Walpole. A mile south-east of the hill there is a quarry of 

 red and white grits or flagstones dipping W. N. W. Half a mile 

 south-east of this quarry, on an island in the swamp, over which the 

 road passes, are considerable outcrops of large conglomerate appar- 

 ently dipping north-westward. 



A specimen of "graywacke "from Wrentham in the rock collection 

 of the Harvard College Mineralogical Cabinet, resembles the coarse 

 gray variety of sandstone in Canton. 



In Canton, on the Boston and Providence Railroad, there is 

 another cutting through rocks of different character, about a mile 

 south of the one described. The strike is N. 60° to 65° E., and the 

 dip 70° N. The joint-cleavages are N. N. E. dipping E. S. E. The 

 strata are conglomerate, sandstone and schists. The latter are light 

 gray and of obscure stratification. They contain dark, cylindrical 

 forms which appear to be branching stems of some kind. Prof. 

 Hitchcock describes a cylindrical stem, perhaps fucoidal, found in 

 hard dark slate in Attleboro at the southern end of this basin, (No. 

 400, State Geological Survey Collections). 



Eruptives, 



It has been very common to resort to imaginary escapes of fluid 

 matter from a vague molten interior of the earth, to account for the 

 existence of intrusive masses of crystalline rocks penetrating and 

 overlying those clearly stratified. The origin of such intrusions, 

 formed at so late a period in the history of the earth as were the ig- 

 neous outflows among and upon the stratified rocks in this neighbor- 

 hood, must be sought in a more superficial region than is generally 

 understood by this non-committal interior. 



Judging from indications constant in regions of metamorphic rocks, 

 and most marked where metamorphism is most complete, molecular 

 rearrangement and crystallization of sediments, the patent facts of 



