CONTRIBUTIONS TO THE GEOLOGY OF MAINE. 
PART II. GEOLOGY OF THE AROOSTOOK VOLCANIC AREA. 
By Herbert E. Gregory. 
CHAPTER I. 
INTRODUCTION. 
GEOGRAPHY. 
The area considered in the present paper includes the section of 
Maine known as the " Aroostook country." An examination of the 
map, fig. 1 (p. 12), shows its location in the extreme northeast extension 
of United States territory. 
The region is without natural boundaries, and hence for purposes of 
this report the area is outlined and bounded as follows: On the east 
by New Brunswick; on the north by the St. John River and the Fish 
IRiver Lakes; on the west by a line joining Portage Lake, Ashland, and 
Oakfield, and on the south by a line from Oakfield to Houlton. These 
lines include an area about 75 miles long by about 30 miles wide, which 
is separated from other parts of Maine by a belt of forest land, whose 
monotony is broken here and there by a few rich farms. The natural 
connection is with New Brunswick, and there is nothing in the topog- 
raphy or the character of the soil or the people to indicate when the 
boundary line has been passed. Much of the Aroostook country has 
been settled from the Maritime Provinces, and until a very few years 
ago the outlet for produce and the main line of travel was along the 
St. John River to the city of St. John, on the Bay of Fundy. The 
construction of the Bangor and Aroostook Railroad has largely 
changed this condition of affairs, but the region still reminds one of an 
agricultural island of great richness, reached from the southern part 
of Maine after traversing an uninhabited expanse of forest land. 
The most thickly settled portion of northern Maine is the eastern 
border from Houlton north along the belt of slated limestones (Aroos- 
took limestones). In the vicinity of Houlton this strip is hardly more 
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