based upon general impressions gathered from hasty, bird's-eye- 

 view surveys, rather than detailed and accurate knowledge. 

 During the last decade, various members of the Canadian 

 Geological Survey, and especially Mr. G. F. Matthew and 

 Prof. L. W. Bailey, have greatly extended our knowledge of 

 Acadian geology. Their labors, however, have been mainly 

 confined to New Brunswick ; and Nova Scotia is yet, as 

 regards an accurate knowledge of the comjDosition and relations 

 of the crystalline formations of the province, well-nigh an 

 unknown land. Our knowledge of the crystallines of Maine, 

 also, is wholly inadequate for the purposes of comparative 

 geographic study. In the study of the rocks of Eastern 

 Massachusetts presented here, a detailed comparison of this 

 region with those to the north-east has not been attempted ; 

 our knowledge, as just stated, not being considered ripe for 

 accurate generalization over so wide an area. Yet, although 

 the end kept steadily in view has been merely to advance in 

 some degree our knowledge of the character, distribution, and 

 relations of the various rocks occurring in a limited district, 

 it is hoped the way has been, in a measure, prepared for the 

 higher study hinted at. 



TOPOGRAPHY AND GENERAL OUTLINES. 



The extent of territory coming within the scope of this paper 

 is intended to be shown by the smaller of the two accompany- 

 ing maps. It includes in a general way all that part of the 

 State east of the north-south range of highlands of which Mt. 

 Wachusett is the culminating point, and north of the Rhode 

 Island boundary ; comprising the whole of Essex, Middlesex, 

 Norfolk, and Suffolk Counties, the eastern half of Worcester 

 County, and the northern portions of Bristol and Plymouth 

 Counties. As shown by the map, the length and breadth of 

 the district are approximately equal, and the area is not far 

 from three thousand square miles, or about three-sevenths of the 

 State. 



