36 • NEW YORK STATE MUSEUM 



reservoirs are located. The house of Mr W. Tenbroeck stands on 

 the bar, the head of which was made 275 feet by aneroid. The 

 map contours the bar from 280 down to 240 feet. The profile 

 (plate 10) makes 275 feet the precise altitude for the estuary at 

 this point. 



The smooth tract 6 miles east of the Hudson, stretching several 

 miles past Livingston, Blue Stone and Manorton, shows the leveling 

 and smoothing effects of standing water. Numerous kettles indi- 

 cate that ice blocks of the glacier margin were buried in the detritus 

 swept in by the land drainage from the east, perhaps aided by 

 glacial outwash. The smooth kettle plain southeast of Livingston 

 is contoured at 240 feet. The full height of the open estuary, 260 

 feet, is registered in the bare shales about the kettle area. 



At Greendale, 4 miles east by south from Catskill, good bars 

 were seen by the writer and Professor Chadwick at over 240 feet, 

 by the map; and the top of the hill is planed at 260 feet. 



Coxsackie sheet. This sheet shows the broad clay plains west 

 of Hudson, traversed by the West Shore Railroad. Except for 

 a space west of New Baltimore these plains extend the whole length 

 of the quadrangle. On the north they join the great Mohawk 

 delta, at Ravena and Coeymans. 



The marine plane is about 280 feet at Athens, and rises to 315 

 feet at Coeymans. The clay flats are much below the summit 

 plane; the "Athens flat" being contoured at 120, the West Cox- 

 sackie plains at 120 to 140, the New Baltimore at 200, and the 

 Ravena at 200 feet. The deposits were laid in deep, quiet waters, 

 and the material was probably contributed in larger part by the 

 earlier strong glacial drainage through the Mohawk valley (164). 



The west boundary of the estuary was here the bold face of the 

 rock hills. The drift had been so fully removed from the high- 

 land by the ice-border streams that the later land drainage found 

 little detritus to pile as sand or gravel, as topping for the clays, as 

 we find southward. The land on the west was thoroughly swept 

 by the glacial flow, and the glaciation and stream work, perhaps 

 repeated, has given the decided allineation, north and south, shown 

 by the map. 



Only two streams were heavy enough to build deltas, and these 

 are not in the open Hudson valley but up stream. One is the 

 Catskill, extending from Leeds to South Cairo. This was years 

 ago the subject of an admirable paper by Davis (37), in which 

 he makes the altitude of the estuary waters at South Cairo about 

 275 feet. This proves to be the theoretic height, and the delta is 



