MANSFIELD: ROXBURY CONGLOMERATE. 191 
Tur HARVARD CONGLOMERATE.— Distribution. The Harvard 
Conglomerate occupies only a limited area near the town of Harvard, 
Mass. ‘The best exposures are found on the top of the hill about half 
a mile north of the center of the town. Sandstone and grit are 
interbedded with the conglomerate, which on the north is over- 
laid apparently conformably by phyllite. No igneous rocks appear 
to be associated with the series. 
Texture of the Conglomerate. No definite gradation in texture 
was seen, and no definite relation between the size and shape of the 
pebbles was observed. Large and small pebbles alike were angular 
or subangular. 
Bedding. The bedding of the conglomerate and sandstone is of 
the banded type. No lenses, cross-bedding, ripple-marks nor local 
unconformities were noted. 
Relations to Subjacent Rocks. No definite data with regard to the 
relations of the conglomerate to the subjacent rocks are at hand save 
Burbank’s statement that it is “interstratified with the enclosing 
gneiss” (p. 224-225). No indications of ancient glaciated surfaces 
are to be found. 
GENERAL SUMMARY.— (1) In each of the three basins arkose 
occurs at certain places along the border but it does not appear in the 
Harvard Conglomerate. 
(2) Conglomerate occurs in all three basins, interstratified with 
finer sediments. The same relation is seen at Harvard. 
(3) Contemporaneous igneous rocks occur in all three basins but 
not at Harvard. They attain greatest importance in the Boston Basin. 
(4) The conglomerate in the Boston Basin grades into finer rock 
north, east, and south. In the Norfolk Basin the gradation from 
coarse to fine is from north to south in the northeastern part and less 
distinctly in the opposite direction in the southwestern part. In the 
Narragansett Basin the conglomerate becomes coarser toward the 
south. In the Boston Basin the decrease in coarseness consists 
mainly in a change in the relative proportions of gritty or sandy 
materials in the rock rather than in a difference in the size of the 
pebbles. In the other basins this feature is not so clearly shown. 
No direction of gradation was observed in the Harvard Conglomerate. 
(5) Bedding is not well developed in the coarsest conglomerates 
but is better shown where the finer sediments appear. Banding is the 
prevalent type. 
(6) Lenses are of relatively infrequent occurrence and tend to be 
