tlEPORT OF THE DIRECTOR igi2 2^ 



from 500 to 600 feet, and they extend practically throughout the 

 whole length of the Dannemora quadrangle. It is evident that 

 these beaches correlate with the Cobblestone hill bars and other 

 detached features on the Mooers quadrangle that formerly were 

 puzzling. 



Being specially developed in the town of Peru these bars in 

 the " Vermont " plane will be called in this report the Peru 

 beaches. This shore exhibits all the characters which argue for 

 the marine origin of the Covey hill beaches. Taken in connec- 

 tion with the features on the adjacent Mooers quadrangle they 

 afford an excellent illustration of the lack of value of negative 

 evidence in study of shore lines, and the error in judging confi- 

 dently from a single district or a limited area. 



The Peru (" Vermont '') shore phenomena are found to be well 

 developed southward throughout the Champlain valley, on both 

 sides of the valley, and to lie far above the P'ort Edward divide. 

 They have been mapped on the Vermont side at Burlington, 

 Middlebury and Brandon. The plane declines from 700 feet on 

 the international boundary to 660 feet at Cobblestone hill, 520 feet 

 near Ticonderoga, 440 feet near Glens Falls, and 390 feet near 

 Mechanicville. The slope of the plane is a little over two feet 

 a mile. These beaches are not the highest or summit bars of 

 the region but were formed after some uplifting of the land had 

 taken place. Their strength suggests that they represent a rela- 

 tive pause or a slower rate in the land uplifting. 



The highest well-developed bars found on the Dannemora 

 quadrangle are 706 feet in height, and lie west of Peru vil- 

 lage. Behind the highest shore features throughout the quad- 

 rangle lie glacial drainage channels, terminating in deltas. These 

 channels and deltas definitely determine the height of the stand- 

 ing waters during the recession of the ice front. This altitude 

 on the Dannemora quadrangle was over 700 feet. 



Northward the summit plane of the Champlain waters during 

 the time when the ice sheet was waning is represented by 

 beaches at Shea's Lines, on the Canadian boundary, south of 

 Covey Hill post office, at about 750 feet; and also by the series 

 of good bars at Cannon Corners, with an altitude of 750 feet. 

 Southward the summit of the standing water is shown in various 

 localities and specially at Port Henry. In the Hudson valley it 

 is well shown. It is found that many cities and villages on both 

 sides of the valley are located on broad summit plains of deltas 



