322 J. F. Kemp — Buried Channels Beneath 



Hole 20 at 580 ft. failed to get through the bowlders, so that 

 we only know that the bed-rock is still deeper. Hole 21, about 

 700 feet from the west bank, stopped in the bowlders at 475*3, 

 so that we only know here that the bed-rock is deeper. It will 

 be driven farther. Hole 18 at approximately 500 ft. from the 

 bank was probably very near the bed-rock if not on it. The 

 casing became bent and the hole was lost. The drillers believed 

 that the bed-rock had been encountered at a shelving point so 

 that the casing glanced off. This is not improbable, although 

 a shelving bowlder is also a possibility. 



If we believe that the great ice sheet found a Y-shaped river 

 valley in the Highlands and operated to change its section to 

 the characteristic U-shape, then the bottom ought to flatten 

 rapidly beyond hole 10, even if it had not already done so at 

 this point. It is anticipated that future holes which are now 

 being driven will find the bed-rock at depths not very much 

 greater. 



We are justified in inferring that on the retreat of the ice 

 this gorge was left with some 200 ft. of bowlders and sand on 

 its bottom. Upon this foundation subsequent water deposited 

 about 200 ft. of sand, gravel, and sandy clay. Either a slight 

 readvance of the ice sheet or floating ice then yielded the upper, 

 thin bowlder bed, after which only fluviatile conditions pre- 

 vailed. If we do not credit the great glacier with much eroding 

 power, then the continent must have been elevated decidedly 

 over 600 ft. in order to provide a run-off. But if we believe 

 that the ice-sheet operated to deepen this channel, then this 

 amount of elevation is not absolutely necessary. The heavy, 

 bottom bowlder-bed indicates that after the retreat of the ice 

 fluviatile scour has not affected the bed-rock. 



The Little Stony Point Crossing. — About a mile south of 

 Storm King a point juts out from the east bank called Little 

 Stony. The river narrows to 2,360 ft., and a line of wash- 

 borings was made with the results shown in fig. 17. No one 

 of them reached 200 ft. Three diamond drill-holes were also 

 sunk, of which the deepest, near the middle of the river, 

 reached 322*2 ft. They all stopped in bowlders, so that to 

 this extent the deep gorge is corroborated. 



The Arden Point Crossing. — Three or four miles south of 

 the Little Stony crossing and about a mile below West Point 

 is the Arden Point line, to which some exploration has been 

 directed. The shores are in the sedimentary metamorphics 

 of the Highlands, and on fig. 18 are called Grenville, using the 

 name current in the Adirondacks and Canada. The river is 

 only 2,120 ft. wide, so that the shortest section beneath its 

 water of all those tested is afforded. Wash-borings, the only 

 ones used, reached depths of 220 ft. and less. The line, how- 



