ANCIENT WATER LEVELS OP CHAMPLAIN— HUDSON VALLEYS 173 



the map [pl.29] there is a similar cobblestone ridge at about 

 800 feet elevation (aneroid). Over all the northern half of the 

 quadrangle these isolated deposits are separated by an interval 

 of about 100 feet from the next high mark of wave action, begin- 

 ning the record along the international boundary at about 620 

 feet. In the southeastern half of the sheet, wave-made traces 

 are visible from the top of Cobblestone hill down to the low 

 ground on the east of the area. 



Beginning on the international boundary in the region of Arm- 

 strong's Bush, wave-heaped materials begin to appear at about 

 540 feet in a closely crowded series of ridges of angular shingle 

 extending down to about 360 feet. Southward the upper limit 

 of this group falls off in elevation and in the vicinity of Wood 

 Falls on the Big Chazy the highest clear beach is found at 500 

 feet. In the southern part of the sheet this lower series is not 

 distinguishable from the upper series in any manner which I have 

 been able personally to devise. 



The accompanying map [pl.29], shows the location and extent 

 of the more distinct traces of these and other beaches. 



Shore lines about Covey hill, Canada. Reference has already 

 been made to the occurrence of a well defined beach taken by 

 Mr Gilbert to be the upper marine limit on the north side of 

 Covey hill at an elevation of 450 feet [see p.162]. On plate 25, 

 I have attempted to delineate the position of this beach for a 

 portion of its extent. It is a very strongly developed beach for 

 this district with well worn pebbles on its seaward face. Below 

 it occur others toward Ste Antoine and Vicars. Accepting the 

 terraces which come above this beach as made by waters escaping 

 along the ice front, this 450 foot beach is the highest one found to 

 extend from the beaches of the Champlain valley around the 

 northern face of Covey hill. Its westward extension is known at 

 a number of points near Sun, East Constable, Potsdam and places 

 still farther westward. But in the district southwest of Malone 

 the ground becomes so much broken up in the form of short hills 

 that tracing it is difficult without a good topographic map as a 

 guide to localities in which wave action should be looked for. 



The vicinity of Covey hill is of critical interest in the solution 

 of the problems relating to all the shore lines of the Champlain 



