Dodge.] 410 [February 3, 



S. S. W. direction, corresponding to the course of the streams which 

 drain this area and empty on the north into Charles Eiver. 



In Newton, the conglomerate extends but little north of the Boston 

 and Albany Railroad. Near Newton Corner, on Tremont Street 

 between Park and Moore Streets, there is a quarry of schistose con- 

 glomerate with pebbles of green slate, and varying to a hard, sandy 

 variety. The mass of the rock here is smooth and has the slippery 

 feeling of steatite. The peculiar composition of the crystallines re- 

 peats itself noticeably in many instances in these rocks derived from 

 them. In West Roxbury, I have found serpentine aggregated on the 

 pebbles of loose conglomerate. Small particles of magnetic iron are 

 frequently disseminated through the sandstones. 



The prevalence of pebbles of reddish felspathic crystallines in the 

 conglomerates between Grove Hill Cemetery, Newton, and Allston 

 Street, Brighton, is rather noticeable. 



If the marking in the slate pebbles found in conglomerate north of 

 Beacon and west of Cambridge Streets, in Brighton (as well as in a 

 boulder in Canton), can be taken as significant of the identity of 

 these slates with those in place at Somerville and Quincy, which have 

 similar markiags, this gives a valuable test of the relative ages of the 

 two rocks. 



The most westerly exposure of conglomerate I have seen is in Need- 

 ham, about three-quarters of a mile east-north-east of Wellesley Sta- 

 tion, where at the north-western end of a long hill, there is an outcrop 

 of the rock, apparently in place there. It is abundant between Rose- 

 mary Brook and Charles River, and just south of the bridge at New- 

 ton Upper Falls it forms a gorge through which the river runs. 

 Half way from Rosemary Brook to the river and about three- 

 quarters of a mile south of the road from Newton Upper Falls to 

 Grantville, the strike is N. E. or N. N. E, and the dip northwest- 

 ward. A pebble of ash colored schist in the rock here resembled the 

 laminated felsites near Hyde Park. Next, south of this is a great 

 ledge with large round quartzite pebbles such as may be found in 

 situ at Natick. The cement is chloritic and scanty. 



The ridges of conglomerate following the line of strike from this 

 place across Newton, Brookline and Roxbury, are particularly high 

 and the outcrops unusually extensive. At the quarry just north of 

 the Roxbury Station of the Boston and Providence Railroad the con- 

 glomerate had layers of red sandstone. The ledge has been nearly 



