170 NEW YORK STATE MUSEUM 



, retreat of the ice sheet is shown by the fact that the surface of the 

 till sjmr above this level is deeply cut by what 1 take to be marks 

 of wave action. Well rounded gravel is encountered at approxi- 

 mately this same level farther east on the northern face of Trem- 

 bleau monntaiUy indicating efificiont wave action there suflScient 

 to pocket the material between ledges. 



There is a noticeable grouping of shore lines in Port Kent 

 between 200 and 260 feet; back of Port Kent about 350 feet; a 

 rather i>ersistent shore line at or just below 500 feet and in 

 favored situations from 500 up to 585 feet. The mpst marked 

 wave action in this range is at 350, 500, and from 585 to 590, 

 because these last are the highest seen. A search above the GOO 

 foot line over the top of Trembleau mountain failed to show higher 

 signs of wave action. 



A 500 foot delta plain is extensively developed about Keeseville, 

 both east and west, and to the south as well. About 1 mile north- 

 east'of Keeseville, a hillock rises up on the sloping surface of the 

 delta plain with what a})pears to be a circular shore line as shown 

 on the map. The strength of the delta building and that of the 

 shore line at the 500 foot line are rather marked. 



The next marked delta stage in descending order coincides with 

 the base of the cliff above described at about 340 feet. A fragment 

 of delta terrace lying between Wickham marsh and the Ausable, 

 having a surface at about 250 feet elevation, accords with the 

 wave lines in Port Kent village. 



As noted on the diagram, plate 28, these shore lines and deltas 

 appear to be correlated with a tilted series of strong and weak 

 lines of wave action and deltas traceable southward from the 

 international boundary. It is probable, as I have attempted 

 to show in chaj)ter 10, that Ihe uj)por marine limit at Port Kent 

 is found at about 340 feet. Delta building at this stage would 

 have covered the Ausable chasm ; hence, it follows that the chasm 

 must have been cut since the land began to rise from the marine 

 limit. 



Fossil marine shells have long been found in the sands of the 

 delta south of Port Kent station. An account of these shells will 

 !)(' foMiHl on page 212. 



