of the Hudson River. 7 



that despite the precipitous sides of Storm King and Break- 

 neck Mountains no fault played any part in locating the river 

 in its present course. On the contrary, it has cut its way 

 downward into the granite without being directed by any plane 

 of weakness. As has been suggested already by Dr. C. P. 

 Berkey,* the river is doubtless a superimposed one and was 

 probably guided at the outset by some soft overlying beds so 

 that it became intrenched in the hard, crystallines. At a time. of 

 greater relative elevation of the land with regard to the sea, and 

 presumably in the closing Tertiary period, as the Glacial epoch 

 was approaching, the river cut its channel below the present 

 surface of the Hudson and part of the way down to its present 

 bed-rock. Reserving the further elaboration of this topic for 

 a moment, it will be taken up again further on. 



A very remarkable feature of the tunnel is the small 

 amount of water which it yields. Although the tunnel is 3022 

 ft. from shaft to shaft, is 18 ft. in diameter, and traverses 

 jointed rocks beneath the great river, the wall-rock is prac- 

 tically dry throughout much the largest part of its course. The 

 west shaft and over 2000 ft. of the tunnel next it at present 

 only yield to the pumps 30 gallons per minute. Much of this 

 comes from the shaft itself and the larger part of the remainder 

 from a jointed portion with an appreciable drip near station 

 960 (see fig. 4). At the time of the writer's visit, Feb. 6, 1912, a 

 bench had been left at station 942 + 60, to confine the more abun- 

 dant water from the faults to the eastern 1000 ft. of tunnel. 

 At this date the east shaft and approximately 1000 ft. of 

 tunnel draining into it yielded about 235 gallons per minute — 

 a goodly part of which was derived from the shaft itself, near 

 the upper pump chamber shown in fig. 2. 



It is a very impressive experience to be lowered in the great 

 shaft on the west bank to a depth 1100 ft. below sea-level, to 

 walk for 2000 ft. through a tunnel 18 ft. in diameter beneath 

 a great river and to observe wall-rocks which are practically 

 dry except at one or two limited points. One may then con- 

 tinue another 1000 ft. and meet the same conditions except at 

 the two small faults. The conclusion is greatly strengthened 

 that the amount of ground-water in the rocks beneath the 

 surface has been much exaggerated by the great majority of 

 writers who have discussed the" subject in the past. 



The character of the water is also of much interest as com- 

 pared with that of the Hudson overhead. Analyses show that 

 the Hudson itself at the Storm King Crossing varies appar- 

 ently at different stages of the tide. At the ebb with the 



* C. P. Berkey, Geology of the New York City (Catskill) Aqueduct. Bull. 

 146, N. Y. State Museum, p. 95, 1911. Besides being a scientific record of 

 observations of unusual accuracy, this Bulletin is an illustration of the appli- 

 cations of geological studies to a great engineering problem. 



