ROCKS OF MOUNT DESERT ISLAND 583 



In the absence of the authors the remaining papers were read by title, 

 in general session. 



OCCURRENCE OF OEM MINERALS IN SAN DIEOO, RIVERSIDE, AND SAN BERNAR- 

 DINO COUNTIES, CALIFORNIA 



BY GEORGE F. KUNZ 



The paper will be published by the California State Mining Bureau. 



ROCKS OF MOUNT DESERT ISLAND, MAINE 

 BY PERSIFOR FRAZER 



In general terms it may be said that Mount Desert island is the remains of an 

 area, once much higher than now, which is distinguished by a series of narrow 

 elevations and valleys of which the axes are nearly parallel and trend a little west 

 of north and east of south. The northern and southern and western shores are 

 low lands, though generally showing a rolling surface ; but the easternmost edge 

 of the island, and especially a zone which traverses the island a little below its 

 mid-latitude, running about east 25 degrees north and west 25 degrees south, 

 exhibits bold heights which have received the names of mountains, though none 

 of them exceeds 1,555 feet by the Coast Survey levels. (The highest point of 

 Green mountain from two sets of uncorrected barometer observations made by 

 me in favorable weather gave a mean of 1,565 feet from the steamer wharf at Bar 

 harbor to the foot of the U. S. Coast and Geodetic Survey signal on the summit.) 

 Passing over this zone from east to west, we have Newport and its associated Picket 

 mountains, Dry mountain, Green mountain, Pemetic mountain, The Bubbles, 

 Jordan mountain, Sargent mountain, Little Browns mountain, Browns mountain, 

 Robinson and Dog mountains, Beech mountain, and Western mountain with its 

 two peaks divided by a deep ravine. The island is about fifteen minutes of lati- 

 tude in extent north and south and about the same number of minutes of longi- 

 tude in breadth east and west, including Bartlett and Hardwood islands; the 

 average distance apart of its elevated ridges on the line of its greatest breadth is 

 little more than a mile. Its structure can not be considered separately from the 

 main land, to which the island is joined by a bridge at Trenton, and it evidently 

 represents a survival of the southern edge of part of the coast due to the hard and 

 resistant rocks of which it consists, and which have conferred upon it the distinc- 

 tion of the most elevated land on the Atlantic coast within the domain of the 

 United States. 



The principal sources from which information may be gathered as to the geology 

 of Mount Desert island are W. O. Crosby's paper on the geology of Frenchmans 

 bay,*N. S. Shaler's beautifully illustrated report on the Geology of Mount Desert,! 

 and the introduction to the Flora of Mount Desert, Maine, by W. M. Davis. t 



Professor Shaler recognizes : 



I. (1.) A gnarled and thick deposit of chloritic schists on the west side of the 

 island. 

 (2.) A nearly similar but less distinctly schistose terrane on the east side 

 between Schooner head and Rodicks cove. 



* Vol. xxi, pp. 109-117, Proc. Bos. Soc. Nat. Hist. 



+ 8th Annual Report of the U. S. Geological Survey, part ii, 188C-'7, pp. 993 to 1061. 



J Rand and Redkeld : John Wilson and Son, Cambridge, Mass. 



