184 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of Canton Junction and the impregnations of the conglomerate 
referred to in the previous chapter are the only known exposures. 
The field, however, is thickly covered with glacial material and it 
may well be that many important occurrences lie hidden. 
Texture of the Conglomerate. Variations in the texture of the con- 
glomerate in the northeastern part of the basin are best seen in the 
rocky ridge east of the Neponset River (Dedham IV, southward from 
I 22). At the northern end the conglomerate is very coarse., Sub- 
angular pebbles eight or ten inches in diameter are numerous and 
boulders more than two feet long are not uncommon. Southward 
the conglomerate grades through various alternations into grit and 
shaly sandstone. Farther east similar coarse conglomerate occurs 
on the south side of Houghton Pond, on the south slope of Bear 
Hill, at ledges three-quarters of a mile farther east along the Mona- 
tiquot Stream, and in large broken masses at the northwest end of 
Great Pond. In each of these cases grit and sandstone appear to 
the south but no gradation is observed. 
In the southwestern part of the basin the coarsest conglomerate occurs 
about half way between Walpole and Pondville (Franklin VIII, R S 
20-21). There the pebbles of the conglomerate sometimes exceed 
one foot in diameter but the rock as a whole cannot be said to be so 
coarse as the conglomerate above described. At this locality the 
pebbles become larger toward the south but the gradation. is not so 
marked as in the other case. At Pondville (Franklin VIII, K 29) 
the conglomerate associated with the finer sediments is relatively 
fine and the pebbles consist of white quartz. Neighboring ledges 
of conglomerate extend northwest from M 30 to L 29. At the south 
these ledges consist of fairly coarse conglomerate of the normal type, 
with pebbles five inches or more in diameter, but northwestward the 
latter becomes finer and alternates with sandstone and slate. Thus 
in a general way the direction of gradation in texture in the southwest- 
ern part of the basin is opposite to that of the northeastern portion. 
As in the Boston Basin the smaller pebbles attain the greatest 
degree of rotundity but even these can seldom be described as well 
rounded. ‘They are more properly termed subangular or rounded. 
Bedding.—- As in the case of the Boston Basin the bedding is best 
displayed where the finer sediments occur. Satisfactory determina- 
tions are often not easily obtained. Nevertheless the proportion of 
the outcrops observed that display features of bedding is greater 
in the Norfolk Basin than in the Boston Basin. Many boulders 
and large masses of the sedimentary rocks not certainly in place 
