BURR : MELAPHYR OF BROOKLINE, BRIGHTON, AND NEWTON. 61 



tween Greenwood Street and Newton Highlands. It is not seen in the 

 area occupied by this anticline west of the vicinity of Dudley Street. On 

 the south side of Central Street, west of the Charles River, red felsite is 

 exposed within a very short distance of the conglomerate. There is not 

 room, at this point, for the melaphyr to pass between the felsite and the 

 conglomerate. Thus it appears that it does not completely encircle the 

 synclinal area. 



Melaphyr occurs near Newton Upper Falls, on the south bank of the 

 reservoir, and on the Charles River north of Worcester Street. It is well 

 exposed in three ridges on Boylstou Street and Thurston Road, not far 

 east of Upper Falls. These localities are in the middle of the synclinal 

 belt, and trend diagonally across the supposed trend of the slate. At 

 Crystal Lake, Newton Centre, the melaphyr again appears on the border 

 of the slate belt. On Station Street, near Newton Centre, is a small ex- 

 posure. This is nearly east of the Crystal Lake locality and possibly 

 connected with it. It is much nearer the synclinal than the anticlinal 

 axis. 



The northern belt of melaphyr is not nearly so continuous as the 

 southern. It does not appear to occupy an axial position. It seems, 

 from exposures in recent ditches, that the region south of Newton Lower 

 Falls is underlain by conglomerate and slate (Plate 2, Loc. 23). There 

 are excellent exposures on Chestnut Street, south of Commonwealth 

 Avenue (Plate 2, Loc. 24). Conglomerate appears on the shore of Chand- 

 ler's Pond, near Lake Street (Plate 2, Loc. 25). The melaphyr does not 

 appear south of these exposures. If the limits of the conglomerate area 

 be extended, as they should be, to include these outcrops, there will be 

 a much greater area of conglomerate south of the melaphyr than north 

 of it. 



The distribution of the melaphyr does not, therefore, accord with the 

 structure, as interpreted by Professor Crosby. It occurs not only in 

 the anticlines, but in the axis of the syncline. In the northern conglom- 

 erate area it is bordered by a much greater thickness of conglomerate on 

 the south than on the north. In the southern area it is not symmetri- 

 cally arranged about the underlying felsite. It is not continuous about 

 the synclinal area of conglomerate. This irregularity of occurrence is 

 quite in accord with the idea that the melaphyr is intrusive. 



A New Interpretation op the Structure. — Before settling upon 

 this conclusion it is necessary to consider the possibility of a different 

 interpretation of the structure. The broad conglomerate area of Brook- 

 line, Roxbury, and Dorchester is the one well-defined structural unit in 



