BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
104 
idea that the conglomerates of eastern Massachusetts represent 
ancient glacial material worked over by the sea (Shaler et al., 
p- 57). Another view, suggested by Bouvé, (b, p. 40-41) is that 
the conglomerates were formed of rock deeply disintegrated under 
the “highly corrosive” atmosphere of early ages and subsequently 
resorted and deposited by waves. The possibility of fluviatile ori- 
gin for the Roxbury Conglomerate has not been suggested in pub- 
lished accounts, but Professor Woodworth has shown (d, p. 176-177) 
that some portions at least of the Narragansett sediments were depos- 
ited by streams, and in conversations with the writer he has often 
expressed the opinion that the entire conglomerate series of eastern 
Massachusetts is non-marine. The later published views, however, 
still regard the conglomerates as laid down by a transgressing sea, 
during a period of slow subsidence of the land, accompanied by various 
oscillations in level (Crosby, n, p. 461). Similar conclusions were 
reached by La Forge in his unpublished report on the Geology of 
Somerville (p. 90). The current tendency of opinion therefore seems 
to be to regard the conglomerate as marine, but it must be admitted 
that the other hypotheses have not been examined with sufficient care. 
In the present paper an attempt will be made to consider carefully 
various hypotheses in order to determine if possible which has the 
greatest weight. 
Score or FieLD Work.— The Roxbury Conglomerate is abun- 
dantly exposed in a number of separated areas. An attempt has 
been made to see the principal outcrops in each of these regions, 
with the idea of getting a general view of the whole field rather than 
of making a detailed study of particular areas. The work has also 
included a similar, though not so extended, study of the Norfolk 
Basin sediments. Several trips have been made into the Narragan- 
sett Basin, more especially to the districts in the vicinity of Attle- 
boro, Seekonk, Tiverton, and Newport, and localities, near Worces- 
ter and Harvard, Massachusetts, have also been visited, the latter in 
company with Professor Jaggar. The Parker River, Bellingham, 
and Woonsocket areas have not been seen by the writer. 
Score or Lazoratory Worx.— Numerous selected specimens 
collected by former students. in geology at Harvard University and 
by the writer, from typical localities, have been examined and stu- 
died. Their character and composition have been determined by 
means of a low power lens on natural and polished surfaces and 
