236 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
be as much as 300-400 feet in the widest portion. Southward the 
conglomerate apparently thins out. 
Metamorphism. The highly fractured and metamorphosed con- 
dition of the conglomerate is described by both Burbank and Crosby, 
the latter deriving most of his information from the former. In the 
field two directions of schistosity were noted, one nearly parallel to 
the styke, with an easterly dip of about 40°, the other with a northeast 
strike and a more gentle southeasterly dip. A description of the prin- 
cipal characteristics of the pebbles has already been given (page 
167). The suggestion is strong that the conglomerate was formed 
in situ by the disruptive action of the shearing and crushing forces 
upon layers of quartzite but the conglomerate cannot be traced along 
the strike into unaltered quartzite. Moreover, the resemblance of 
many of the fragments to water-worn pebbles is very striking. Some 
of the latter are broken and the pieces separated, while others are 
elongated into distorted lenses (Figure 10, A and B). On the whole 
the general impression left by a study of the rock is that it represents 
an original conglomerate, that has suffered dynamic metamorphism at 
a depth too slight to permit the production of much plasticity. 
Summary. The Harvard Conglomerate forms a small wedge- 
shaped area extending two miles southwest from the vicinity through 
the town of Harvard. It strikes nearly north-south and has a steep 
westerly dip. Its stratigraphic position and age are uncertain but it 
may form part of the northeast extension of the eastern limb of the 
syncline in the Carboniferous rocks just east of Worcester, as worked 
out by Perry and Emerson. The most striking feature of the con- 
glomerate is its brecciated, stretched, and generally metamorphosed 
appearance. 
GENERAL SUMMARY.— Structure. The Boston Basin is probably 
bounded by faults on the north and south and is characterized by 
eastward pitching folds, broken by faults. 
The Norfolk Basin is divided into two areas, northeast and south- 
west. The northeast region is probably bounded on the north and 
south by faults and has a relatively simple monoclinal structure. The 
southwest area is characterized by folds and transverse faults. Its 
southern boundary is, in part at least, a true sedimentary contact. 
The Narragansett Basin is bounded mainly by sedimentary contacts 
and is characterized by a system of large and relatively simple folds. 
The strikes of the faults and of the axes of the folds in the Boston 
and Norfolk Basins are prevailingly east-northeast. The faults in the 
