301 J. F. Kemp — Buried Channels Beneath 



with the new sources of water which are to be tapped from 

 Esopns Creek in the Catskills for the rapidly growing popula- 

 tion of the metropolis. The writer would express his acknowl- 

 edgments to J. Waldo Smith, C.E., Chief Engineer, for 

 permission to use the data in this way, and to Robert Ridg- 

 way, C.E., Department Engineer of the Northern Department, 

 within whose territory nearly all the ground here covered is 

 embraced. Erom the Division Engineers, A. A. Sproul,W. 

 E. Swift, L. E. Brink, L. White and C. E. Davis, and from 

 J. F. Sanborn in charge of the geological features and records, 

 every facility has been received. • Alfred D. Flinn, C.E., 

 Department Engineer of Headquarters, has written of the 

 Storm King crossing.* The writer has constantly worked 

 with his colleague, Dr. C. P. Berkey,f in the field and has dis- 

 cussed results in the laboratory. The interpretations here 

 given and the details of local geology are based upon the 

 observations and inferences of both. 



The General Line of the Aqueduct. — The main reservoir 

 for the new supply will be developed by a huge masonry dam 

 which will cross and impound Esopus Creek at the Olive 

 Bridge site, a few miles below Shokan in Ulster County. 

 The dam is to be in the more open country southeast of the 

 Catskills, which are in full view a few miles away. At this 

 point the Esopus is in a deep post-glacial gorge in the Hamil- 

 ton;}: flagstones, which dip at a flat angle to the northwest and 

 are cut into extremely regular blocks by a most remarkable 

 series of joints. The master joints average N. 21 E. ; the next 

 in prominence, K. 71 W., while rarely there are others at .N". 

 9W. andN. 8 E. 



The spillway of the dam will be at 580 ft., so that wher- 

 ever in its course to the city the aqueduct crosses a, valley, 

 the water must be conducted in a pressure tunnel. Since bed- 

 rock tunnels for a clear cross-section of fifteen feet or more 

 are far cheaper than steel pipes, it has been of prime import- 

 ance to keep the aqueduct in solid rock, with sufficient cover 

 wherever it dipped below grade ; at the same time a tunnel 

 whose bursting pressure is from within, rather than from 



* Explorations for Hudson River Crossing of the Catskill Aqueduct, New 

 York City, Engineering News, April 2, p. 358, 1908. 



f Early in the development of the explorations the writer was appointed 

 consulting geologist to the Board. About the same time Prof. W. O. Crosby 

 received a similar commission and a year, later Dr. C. P. Berkey. While 

 the writer has often worked in association with Dr. Berkey, our reports have 

 been made in entire independence of those of Prof. Crosby, with whose ■ 

 results the writer is not familiar. 



\ The name Hamilton is here used in a general sense to include the Hamil- 

 ton, Sherburne and Ithaca. The section embraces practically uniform sand- 

 stones and shales, almost if not quite ' devoid of index fossils, and with no 

 sharp demarcation. It is quite certain, however, that the higher members 

 are included. 



