8 Report of the State Geologist. 



city terminates like a huge embankment, dropping nearly 100' to a similar 

 sand plain below. The lower sands certainly represent delta deposits of the 

 streams in bodies of standing water. Whether that is true of the uppermost 

 is not so certain. What were apparently true beaches were noted at three or 

 four points, but no attempt to trace them could be made. These sand-covered 

 tracts are very level, and quite bare of vegetation, the sand often drifting 

 to a considerable extent. 



Outside of the sand-covered areas the surface drift is largely morainic in 

 character. In many places heavy moraines lie in proximity to, or banked up 

 against the out-lying gneiss ridges. Surface boulders are numerous over most 

 of the district, and their extremely local character is worthy of remark and is 

 most strikingly shown along the line of contact between the Potsdam sand- 

 stone and the Calciferous. 



In passing north from the outermost outcrops of gneiss in Bangor, 



Brandon and Dickinson townships, Franklin county, one descends often into a 



slight depression, then rises on to a morainic ridge with boulders mainly 



of very large and sometimes of gigantic size, composed entirely of gneisses 



precisely similar to those in place to the south. Practically no Potsdam 



boulders are observable. The ridge is not entirely morainic, being composed 



in part of modified drift. It has a variable width, reaching sometimes half a 



mile. To the north of it, with an intervening depression is a much more 



massive moraine whose boulders are of smaller size, and are mainly of Potsdam 



sandstone, while the few gneissic boulders observable are of small size and, 



when compared with the blocks on the other moraine are more worn and give 



the impression of having traveled much further. The facts observed suggest 



that the smaller moraine may have been formed by a local ice movement 



outward from the Adirondack center after the withdrawal of the main ice 



sheet. While they are far from being conclusive they certainly suggest an 



interesting line of inquiry. Such a movement is perhaps a priori to be 



expected and Prof. C. II. Hitchcock has shown that a similar one took place 



from the White mountains center after the withdrawal of the Laurentide 



glacier. 



Sequence of Geologic Events in the Adirondack^. * 



1. The oldest rocks, and also the most widespread of the region, comprise a 

 series of gneisses of somewhat variable character and questionable origin. 

 Owing to profound metamorphism all trace of original structure is lost, their 



* This summary of the geologic history of the region is intended merely to set forth the writers present views 

 concerning that history, and is of course merely tentative, as work is really but fairly begun. These views, it is thought, 

 aro in substantial accord with those held by Profs. Kemp and Smyth, and the history is closely paralleled by that of the 

 Canadian area lying to the northward, as set forth by Prof. F. D. Adams. 



