Annual Meeting.] 282 [May 2, 
area are chiefly middle Cambrian. But we have also proved 
that the lower Cambrian or Olenellus zone has an important 
development here, both east and west of Weymouth Fore River, 
the beds bearing a striking resemblance to those of North Attle- 
boro. Witli the assistance of Mr. Watson, and by taking 
advantage of the opportunities afforded by recent excavations, 
the known area of the Cambrian slates in this region has been 
considerably extended ; and the Monatiquot River belt has thus 
been traced westward to wliere it, apparently, passes beneath the 
Carboniferous strata of the Norfolk Basin." 
"The intricate relations of the Cambrian slates to the Blue Hill 
granites have been carefully traced out over the entire area, and 
illustrated by si)ecial maps and sections. The granite is every- 
where clearly newer than the slate and eruptive through it. Two 
kinds of contacts have been demonstrated — original or igneous 
contacts and fault contacts ; and the distinction of these is 
essential to the correct interpretation of the geologic structure." 
"The stratigraphic and topographic relations of thefelsite form- 
ing the main range of the Blue Hills have received particular 
attention, and satisfactory conclusions have been reached. Its 
topographic prominence is accounted for by the facts that it 
belongs normally above the granite and slate, and that it is a 
harder and more resistant rock. The Blue Hill complex is shown 
to be a composite fault-block, the principal transverse displace- 
ment marking the eastern end both of the felsite area and the 
Norfolk Basin. It is the tilting of this orographic block that has 
separated the Norfolk and Boston Basins, the displacements 
amounting to thousands of feet. These studies indicate that the 
Carboniferous strata of the Norfolk Basin once extended over the 
Blue Hill complex, and also that the faulting and tilting date 
from the Appalachian revolution. It follows from this, that the 
conglomerate series and newer slates of the Boston Basin, the age 
of which has been so long a matter of controversy, are pi'obably 
also Carboniferous." 
"Incidentally to the study of the glacial geology of this region, 
an investigation of the paleontology of the drift hills or drumlins 
has been made. As a result, the number of localities where fossil 
shells are known to occur has been considerably increased ; and 
the number of known species has been at least doubled. The 
list of forms in the drift fauna of the Boston Basin now embraces 
