﻿36 iT. S. Shale?' — Geology of Cobscook Bay District, Me. 



The portion of the report which concerns the glacial and sur- 

 face geology and also that describing the metalliferous veins of 

 this district is omitted in this memoir and will be published 

 elsewhere. 



Topography of the Cobscook District. 



The topography of any district is the key to its geological 

 structure. This is especially the case with an ocean shore, for 

 there the action of the waves and tides removes the detrital 

 materials which often obscure the bed rocks of inland districts. 

 A reference to a general map of the eastern coast line of the 

 United States will show that this shore from New York north- 

 ward has the general topographical form proper to the fjord 

 zone or glaciated shore line of high latitudes. 



The shore is intersected by deep inlets which extend far into 

 the land. Although these inlets have been to a considerable 

 extent effaced by the formation of salt marshes and other de- 

 posits they are still a very conspicuous feature of this district, 

 separating it widely from other coast lines where glaciation has 

 not worked in moulding the land. As will appear from the 

 evidence hereafter to be advanced in this report, the fjord 

 structure, at least along this shore, is the result of the glacial 

 wearing, acting upon a surface of rock of varied hardness. 



Within this glacial or fjord zone of the Eastern United States 

 we may notice several distinct varieties in the shape and char- 

 acter of these inlets. Along the shore north of Long Island 

 Sound and as far east as Cape Cod the inlets are relatively far 

 apart ; their mouths are separated from each other by consid- 

 erable lengths of tolerably straight shore line. Along this 

 southern shore of New England the axes of the inlets lie 

 nearly in the north and south line. The inlets themselves 

 have few islands in their basins, and are in most cases rela- 

 tively narrow. 



From Cape Cod to Cape Elizabeth, the inlets or fjords are 

 fewer in number and have a general east and west trend ; 

 islands are rare and, when existing, are usually composed of 

 drift materials. The relative rarity of inlets on this part 

 of the coast is doubtless to be attributed to the general north 

 and south trend of this part of the shore ; its trend being ap- 

 proximately parallel to the direction in which the glacial ice 

 moved. 



East of Cape Elizabeth the shore trends in a direction nearly 

 at right angles to the course in which glacier flowed. Here the 

 fjord structure is seen in its fullest development : all of the 

 shore line is in fact made up of these inlets. The extent of 

 the indentation may be the better appreciated by the fact that 

 while the direct line from Cape Elizabeth to Eastport is only 



