A. Wandke — Intrusive Rocks. 



Art. XIV. — Intrusive Rocks of the Portsmouth Basin, 

 Maine and New Hampshire; by Alfred Wandke, 

 Foxcroft House, Cambridge, Mass. 



Introduction. 



Location. — The portion of the Portsmouth Basin to be 

 treated in this paper includes 500 square miles of terri- 

 tory that lies partly in the southwestern corner of Maine, 

 and partly in the southeastern corner of New Hampshire. 

 The area under consideration is easily accessible by 

 rail being served by the Eastern and Western Divisions 

 of the Boston and Maine Railroad. The Atlantic Shore 

 Street Railway passes through much of the country not 

 touched by the steam road and thus but little remains 

 that is not easy of access. 



The portion of this area in Maine, except for the imme- 

 diate vicinity of the shore where a thriving business is 

 done entertaining summer visitors, is sparsely settled; 

 that in Xew Hampshire, traversed by several rivers upon 

 which manufacturing industries have been established, 

 although not densely populated, contains a number of 

 prosperous communities. 



Field Work. — This paper is based upon field work 

 done during the years 1915, 1916 and 1917. During this 

 time members of the United States Geological Survey 

 were conducting an investigation of the geology of 

 southwestern Maine and conferences with Dr. L. Laforge 

 of the Survey aided greatly in deciphering the obscure 

 geology. 



Previous Work. — Except for the work of Jackson 1 of 

 the Maine Survey in 1839, and of Hitchcock 2 of the New 

 Hampshire Survey in 1868, but little had been clone in 

 this field. At various intervals since the publication 

 of the reconnaissances of these two men, notes mention- 

 ing the area have appeared in several publications : the 

 clays of South Berwick, Maine, which contain Pleistocene 

 fossils, have been cited in papers dealing with the 

 elevation of the coast of Maine ; Kemp 3 in 1890 described 

 some of the dikes at Kennebunkport and Bald Head Cliffs, 



1 Geology of Maine, Augusta, Maine, 1S39. 



2 Geology of Xew Hampshire, Concord, Xew Hampshire, 1878. 



3 Amer. Geologist, vol. 5, 1890. 



