632 CHARLES EMERSON PEET 



Hudson water body had extended their courses across its old floor 

 to the main stream flowing through the bottom of the trough made 

 by the meeting of the slopes of the old floor. Into this old floor 

 the outlet stream of Higher Glacial Lake Champlain trenched its 

 course at a rate so rapid that the tributary streams were unable to 

 keep pace with it, and they were thus made to descend to their main 

 over steep slopes, which the small streams have not yet succeeded in 

 pushing back far from the present Hudson bluffs (see Fig. 16, A). 



Where the mouth of the Hudson was at this time is a subject 

 for discussion, but it is certain that the land was higher than now and 

 that the Hudson, at least in those regions where it is bordered by 

 clay plain, cut its channel to depths now covered by the waters of 

 the Hudson estuary 10-50 feet deep north of Catsldll. Just how 

 deep the cutting of this channel in the lower Hudson was during 

 Higher Glacial Lake Champlain time is a matter of less certainty 

 for two reg-sons: First, because there has been subsequent filling, 

 as shown by at least 25 feet of clay at Croton, which contains "flags" 

 and shells, while the clay below does not contain them, as reported 

 by the dredgers excavating clay from the river for brick-making; 

 second, because of the occurrence of certain "deeps," the origin of 

 which is a matter of discussion. Such deeps are the New Hamburg 

 "deep" (120 feet), the West Point deep (216 feet), Stony Point- 

 Verplanck's Point deep (102 feet). Fort Washington deep (155 feet), 

 and others. These deeps may be due either to scouring' by the Hud- 

 son during Higher Glacial Lake Champlain time or by the tide since 

 then, or they were original depressions bridged by buried masses of 

 stagnant ice over which the large amount of clay eroded from the 

 upper Hudson during Higher Glacial Lake Champlain time was 

 carried to the sea. If such ice-bridges existed, the deposition of 

 materials carried by the waters of the stream would not be necessary. 

 Subsequent melting of the ice would leave the "deeps. " 



While the origin of these deeps is open to discussion, on the whole 

 it seems certain that the Hudson had cut its channel to a considerable 

 depth below present sea-level before the close of Higher Glacial Lake 

 Champlain time. This necessitates an altitude of the land at that 

 time higher by the amount of the general cutting, at least. 



I F"or ability of a stoeam to scour its channel below sea-level see Chamberlin and 

 Salisbury's Geology, Vol. I, pp. 162 and 184. 



