Dodge.] 412 [February 3, 



§ 



conglomerates, resemble them almost precisely in general character, 

 it is a most natural inference that the conglomerates of this vicinity- 

 are also of the Carboniferous age. 



Norfolk County Basin. 



This band of stratified rocks is of varying width, and extends be- 

 tween the areas of crystallines from near the south shore district at 

 Weymouth, through Braintree, Randolph, Canton, Norwood, Wal- 

 pole, and thence southwestward. Beyond this point I have not yet 

 traced it. 



The strata of this group are in some respects different from any ex- 

 isting elsewhere in this vicinity, so far as I know. The narrow area 

 which they occupy has been so protected from the transverse glacial 

 action by the high crystalline hills to the north and west, that the 

 peculiar red schists and sandstones of Randolph and the adjoining 

 towns, may occur here alone, simply because here only have the con- 

 ditions been favorable for their preservation. It is from their dis- 

 tinctive character that Punkapog pond and river derived their 

 Indian name, which is said to signify stream flowing out of red earth. 

 Other conglomerates in Canton and Walpole are somewhat similar 

 to those so well known in Roxbury and vicinity. 



The valley of Monatoquot River in Braintree is part of a glacia- 

 ted valley south-east of Pine Hill, and the crystallines are hidden 

 beneath the surface. Westward, where they appear, for example, at 

 Franklin Street, this basin between them is narrow; at the Old Col- 

 ony Railroad about a quarter of a mile, at Great Pond from one half 

 to three quarters. At the northern end of Great Pond, there are 

 clear, bright colored sandstones and conglomerates on both sides of 

 the road as far north as the brook. The pudding-stone has pebbles 

 of slate; and in western Randolph, south-east of Punkapog Pond, an 

 erratic has pebbles with the dot-and-line marking above described. 

 This ledge is continued south-westerly on the north side of Punkapog. 



Along the E. N. E. — W. S. W. road south of Punkapog Pond, 

 (Farm St. in Canton, Canton St. in Randolph) for a mile each way 

 from the boundary of the two towns, the outcrops are mostly of fine 

 red sandstone, sometimes of gray conglomerate and sandstone with 

 transparent quartz grains, very hard where it approaches the crystal- 

 lines a mile southwest of Great Pond. 



