522 OGILVIE 



quadrangle were described by F. Bascom, 1 and these are in- 

 serted on the map (Fig. 2). Only the westernmost exposure of 

 these dikes was examined by us.. It was at first thought that 

 Dr. Bascom's big dike might be the same rock-body as one of 

 the dikes of Cabbage Island and the neighboring mainland, but 

 repeated surveys across Linekin's Neck showed that, unless 

 there is displacement by faulting, there are without doubt three 

 parallel dikes. 



The only other literature dealing with the area is comprised 

 in the reports of C. H. Hitchcock. Of neighboring localities 

 Monhegan Island about twelve miles to the southeast has been 

 described, 2 and in Knox County, about fifty miles to the 

 northeast some interesting rock types have recently been 

 studied. 3 



Physiography. 



The topography of the Boothbay quadrangle is characterized 

 by an alignment of ridges and depressions in a direction which 

 changes from due north and south in the southern portion to 

 N. 20 E. in the northern. That is to say, each ridge and 

 valley describes a curve. Tide-water enters all of the larger 

 valleys and extends beyond the northern boundary of the quad- 

 rangle. The tides rush up and down these narrow inlets with 

 great force and undoubtedly have great erosive power. Many 

 tributaries enter the main valleys at abnormal angles, and the 

 branches of the tributaries sometimes enter at abnormal angles, 

 also, so that it is not uncommon for a single stream course to 

 describe three sides of a square. 



It is found that the major features which have produced the 

 adjustment are the strike and the joints of the rock. The 

 principal valleys are outlined by the strike, which has a general 

 north and south trend ; the tributaries are adjusted to the joints, 



1 " Dikes in the Vicinity of John's Bay, Maine," Amer. Geol., 

 XXIII, 1899, pp. 275-280. 



2 " Notes on the Geology and Petrology of Monhegan Island, Maine," 

 by E. C. E. Lord, Amer. Geol., XXVI, 1900, p. 329. 



3 " Some Unusual Rocks from Maine," by Edson S. Bastin, Jour. Geol., 

 XIV, 1906 p. 173. 



