306 Sketch of the Geology of 



ART. XIV.— SKETCH OF THE GEOLOGY OF PORTLAND 

 AND ITS VICINITY. By Edward Hitchcock, Professor of 

 Chemistry and Natural History in Amherst College. Communi- 

 cated April 6, 1836. 



F J 



Having spent the month of May, ISSS, in Portland, 

 Maine, and by the kindness of several gentlemen in that 

 city, having had an opportunity to examine the rocks in 

 the vicinity, I am able to give some account of its geolo- 

 gy. And although a longer residence would be necessary 

 to obtain a complete view of the rocks occurring there, 

 yet, as no account of the geological structure of that region 

 has been published, to my knowledge, I have thought 

 that I might make some statements which would be 

 acceptable to the scientific public. 



The geology of Portland is very simple and intelligible. 

 With the exception of a few limited patches of very 

 recent tertiary strata, and some diluvial and alluvial de- 

 posites, the rocks are chiefly slates of a very early date ; 

 as is proved by their entire destitution of organic remains, 

 and by their standing upon their edges. Gneiss, how- 

 ever, almost destitute of a slaty character, appears on the 

 northwest and north sides of the city, within a few miles, 

 and forms a very extensive deposite. I shall, however, 

 describe these rocks successively ; beginning with those 

 that form the foundation on which the city is built. 



The accompanying geological map and section will 

 enable the Society the more easily to understand my 

 descriptions. In extending the map along the coast south 

 of Cape Elizabeth, in order to exhibit the granite at the 

 mouth of Saco River, I have contracted the distance 



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