MANSFIELD: ROXBURY CONGLOMERATE. 291: 
of the series. The more regular and even bedded portions are sug- 
gestive of quiet fluviatile or lacustrine origin, while the more irregular 
and tumultuous portions of the deposit indicate torrent action. The 
great quantity of large pebbles of relatively fresh granite and the 
abundance of feldspathic material in the sandstones and in the matrices 
of the conglomerates suggest that much material was furnished to the 
streams of that time by glaciers of which no direct evidence now exists. 
Tue HARVARD CONGLOMERATE.— On the supposition that the 
Harvard Conglomerate is Carboniferous it is likely that its history 
may be linked with that of the Carboniferous sediments farther east. 
In spite of the deformation that it has experienced, the form and 
arrangement of some of the pebbles seem to indicate that it was 
originally poorly assorted and that its pebbles were irregular in 
shape, features that tend to ally it more closely with non-marine 
than with marine sediments. The fact that its main constituent is 
a peculiar form of quartzite, unlike any of the known quartzites 
of the region, makes its origin a matter of considerable doubt. If 
the quartzite is an aeolian formation, as suggested by Emerson (see 
page 169), it might have been formed during some halt in the process of 
deposition and later have been rapidly eroded and deposited. The 
general fine texture of the great body of sediments westward, with 
which it seems to be most intimately connected, indicates that the 
region now occupied by them was more remote from the sources of 
Supply than was the case with the sediments of eastern Massachusetts. 
Thus if any connection may be supposed to have existed between the 
Strata in the vicinity of Harvard and Worcester and those of the Narra- 
gansett and other basins farther east, it may perhaps have been such 
as regions in the Indo-Gangetic plain of today bear to the Bhäbar 
regions along the sides of the mountains. It must be admitted, how- 
‘ver, that the relations postulated are highly conjectural. 
Conprtions or Deposrrion.—The character of the basal sedi- 
Ments of the three basins and of the underlying floor indicate that 
at the beginning of the period of deposition the area now occupied 
by the present strata, together with a considerable district of the 
Surrounding country, must have had a more or less subdued topog- 
raphy with relatively low grades. The area does not appear to 
ave been a great valley, as suggested by Shaler (see page 241), 
for no sediments immediately antedating the Carboniferous occur 
etween the latter and the subjacent crystallines, though it is 
