156 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
decrease in size from an average of three or four inches at Newton 
Center to an average of about two or three inches at Auburndale. 
South of this same belt the size of the pebbles increases so that boulders 
eighteen inches in diameter are of frequent occurrence in Brookline, 
while farther south the size again decreases. Eastward, too, in the 
same zone the conglomerate is finer and somewhat more uniform. 
These latter features are well shown by the rock exposed at the great 
Tremont Street quarry on the north side of Parker Hill in Roxbury. 
In the conglomerate zone extending ENE from the Stony Brook 
Reservation the same general gradations in size north, south, and east 
are noted. Along the north shore at the northern extremity of Squan- 
tum and on the east shore of Huit’s Cove at Hingham the conglom- 
erate displays unusual variety in size, the pebbles ranging from less 
than an inch to more than four feet in diameter. 
The shape of the pebbles is also variable. Of the 65 specimens 
above mentioned the pebbles in 32 were noted as unqualifiedly sub- 
angular, while in 20 they were described as subangular to rounded. 
Of the remainder 5 were not described, while 4 were angular and 4 
rounded. On the whole it may be said that the tendency of the pebbles 
is toward rotundity rather than angularity but that in comparatively 
few instances can they be described as well rounded or even rounded. 
The term subangular appears to be applicable in the majority of cases. 
As a rule the finer conglomerates have the more rounded pebbles. 
The areas at Squantum and at Huit’s Cove are no less remarkable 
in the shape than in the size of their pebbles. At the latter locality 
especially every variety of irregularity appears to be represented. 
A careful search for markings that might in any way suggest glacial 
action met with no success. A few instances were observed of pressure 
striations, traceable to dynamic metamorphic action. 
Evidences of deformation were numerous but usually only incipient 
stages were observed. The most frequent was shearing, which, 
though generally not intense, occasionally developed into schistosity. 
In some cases the pebbles were cracked, sliced, compressed, indented, 
stretched and bent but only to a comparatively slight extent. It has 
not been possible to correlate the localities of maximum deformation 
but the evidence now at hand seems to indicate the development of 
zones closely related to the axes of folding. 
The pebbles of the conglomerate show little definite arrangement. 
Sometimes they are sparsely or thickly scattered through a mass of 
relatively fine material. At other times they form massive aceumula- 
tions with comparatively little fine material. In a few cases a rude 
