Fortlaiid and its Vicinity. 337 



^ 



to me that this is a very Important addition to the argu- 

 ment. It may, indeed, be possible to trace erratic boul- 

 ders to their origin without these marks. But without 

 them, it will be difficult to decide whether the detritus 

 was produced before or since the surface had assumed its 

 present levels ; and whetlier more than one deluge has 

 been concerned in bringing it into its present form. No 

 man, however, can examine these grooves, without being 

 satisfied tliat the levels have not essentially changed since 

 the grooves were formed., And then the general uni- 

 formity of direction which they exhibit, over a vast 

 extent of territory, proves that no local causes, such as 

 are now operating, could have produced them. They 

 could not have been formed when this continent consti- 

 tuted the bed of an ocean*; nor by the retiring wave 

 when it wa:s elevated ; but by a rise and flood of waters 



■ 



since this part of the globe assumed its present form and 

 levels. 



^ 



\ 



>/ 





( 



There is scarcely an alluvial deposite in the vicinity of 

 Portland, that i^ extensive enough to deserve a place on 

 the map, or that requires description. The only spot 

 that I have represented as alluvial on the map, is the 

 large sphagneous swamp on the southwest side of the 

 city; and even there, I apprehend that the deposite is 

 rather thin, so as to make ft doubtful whether it deserved 



r 



this notice. But around Portland, and along the whole 

 coast of Maine, are some causes of geological changes 



X ^ i 



now at work, in such a manner as to deserve attention. 

 Indeed, I have been much interested by them. . 



VOL. I. PART III. 44 



