BURR: MELAPHYR OF BROOKLINE, NEWTON, AND BRIGHTON. 55 
1. THe Lack or MenapHyr PEBBLES IN THE CONGLOMERATE. — The 
melaphyr appears to be overlain by a considerable thickness of heavy 
conglomerate. This is particularly true of that in the Brookline area, 
where it occupies the centre of an anticline and is surrounded by the 
coarse basal beds of the conglomerate, dipping away from it in all direc- 
tions. Heavy sediments, such as these, must have been deposited in 
shallow water, within the zone of wave action. It is not easy to see 
how they could have been formed without including some fragments of 
the underlying rock. With this in view the conglomerate has been 
carefully examined. Few pebbles of basic ¢haracter have been found, 
none referable to the melaphyr.t Such evidence is of negative charac- 
ter, and is, therefore, not conclusive, but it has some considerable 
value. 
2. Evipence From Contacts. —The zone of contact between the 
melaphyr and the sediments is evidently a zone of weakness, for its 
place is generally occupied by swamps and other low places. Actual 
contacts are, therefore, not often seen. On Newton Street, Brookline, 
(Plate 2, Loc. 1), nearly opposite the end of South Street, is an irregu- 
lar mass or tongue of melaphyr nearly surrounded by conglomerate. 
This mass cannot be traced far in any direction, but is presumably con- 
nected in some way with the main melaphyr mass to the west. It is 
seen in contact with the conglomerate at several points. It cuts the 
latter in a very irregular way, and without regard for bedding or 
structure. It is certainly not a flow nor even an intrusive sheet. It is 
best regarded as an irregular tongue or offshoot from the main melaphyr 
mass. The rock at this point is the typical melaphyr and is not to be 
confounded with the later traps. 
Farther westward, on the south side of Brookline Street (Plate 2, 
Loc. 2), the melaphyr is again exposed in contact with conglomerate. 
The melaphyr at this point is not over one hundred feet wide and is 
flanked by conglomerate on both sides. The only contacts exposed are 
on the northern side of the melaphyr. This would be the lower side if 
the rock represented a flow. This contact is unmistakably igneous. 
The hard sediment has been fused, in contact with the igneous rock, to 
an homogeneous red mass which has the appearance of felsite. It is 
unfortunate that the southern contact is not shown. It is, however, 
hardly possible that the melaphyr can bea flow, for it ents the sedi- 
ments vertically while the latter have a prevailingly gentle dip to the 
1 Professor Crosby (’89, p. 10), however, states that the conglomerate contains 
fragments of the melaphyr. 
