4 



Portland and its Vicinity. 307 



F " 



scale can produce no error. The section passes from the 

 south east to the north west through Portland, crossing 

 Cape Elizabeth at its northern extremity in fact : but I 

 have introduced the rocks from its southeastern ex- 

 tremity, at the light houses; and have also supposed 

 Jewell's Island to be removed southwesterly, so as to 

 fall in with the line of the section. But as the direction 



1 



of the strata in all this region is almost exactly northeast 

 and southwest, this supposed movement of interesting 

 rocks, so as to bring them into a line, can cause no error 

 of importance in our inferences. 



Talcose and Mca Slate and Quartz Rock. 



w 



I commence with these rocks, because they form the 



g W 



basis of the peninsula on which Portland stands. In 

 many places^ one finds them extremely distinct and well 

 characterized. But they pass into one another so insen- 

 sibly, and are interstratified so fi-equently^ that I found it 

 impossible to separate them upon the map. I think that 

 talcose slate decidedly predominates; especially on the 

 islands of Casco Bay, Next in quantity is mica slate ; 

 which sometimes approximates, in its character, to argil- 

 laceous slate. Quartz rock is the least abundant; yet 

 sometimes we see its strata quite distinct ; as for instance 

 on the shore at the northeast extremity of the city ; 

 where also, we find well characterized talcose slate, ap- 

 proaching even to soap stone. At Harpswell is a quarry 

 of soap stone, which has been wrought to considerable 

 extent ; but is now nearly exhausted. I have not visited- 

 it ; but presume that bed to be connected with talcose 



slate. 



The southeastern part of Cape Elizabeth is composed 





