66 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



of the conglomerate. If melapliyr were associated with these beds, it 

 also might remain unrevealed. Even if this be true, however, the occur- 

 rence of melaphyr in association with beds higher in the series remains 

 unaccounted for. 



It appears, therefore, that neither under the former interpretation nor 

 under that which is offered here, is the melaphyr always associated with 

 the basal beds of the conglomerate, or, indeed, with any definite horizon. 

 On any interpretation, the occurrence of the melaphyr in association with 

 sediments of all kinds, from the coarse conglomerate of Brookline to the 

 slate of Allston, is suggestive of a considerable vertical distribution. 



Evidence from Structural Details. — There are some details of 

 structure which have a bearing on the general question. At various 

 points about the periphery of the Brookline area, small, isolated ex- 

 posures of melaphyr are seen in contact with conglomerate. These do 

 not differ, lithologically, from the larger mass. It is reasonable to sup- 

 pose that they are connected with it. As the conglomerate dips away, 

 in all directions, from the central area, it is clear that the melaphyr in 

 these exposures is associated with sediments higher in the series than 

 those which surround the main mass. In all cases the smaller masses 

 are intrusive into the sediments. This suggests that the main mass also 

 is intrusive. 



The conglomerate on the north bank of the reservoir, at »Newton 

 Upper Falls, dips away from the melaphyr on the south bank. The 

 rock walls are but a few feet apart. It is evident that the dip of the 

 conglomerate is not sufficient to carry the lower beds exposed above 

 the melaphyr cliff. The strike of the conglomerate varies by about 12° 

 from the trend of the parting between the two rocks, carrying it obliquely 

 toward the melaphyr. Conglomerate, outcropping near Eliot Station, on 

 the Boston and Albany Railroad, strikes toward melaphyr on the oppo- 

 site side of the tracks (Plate 2, Loc. 8). On Walnut Street, Newton 

 Centre, conglomerate, on the east side of the street, strikes directly into 

 brecciated melaphyr on the west. On the corner of Commonwealth Ave- 

 nue and Valentine Street is a small exposure of conglomerate which strikes 

 toward the melaphyr mass. In the grounds of the Golf Club, on Centre 

 Street, slate strikes directly across the trend of the melaphyr. On 

 Foster Street, Brighton, sandstones, on opposite sides of the melaphyr 

 mass, strike toward each other. These occurrences indicate deformation 

 in the sediments preceding or contemporaneous with the intrusion of the 

 igneous rock. 



On the east side of Chestnut Hill Avenue, Brighton, the conglomerate 



