EXAMPLES OF STREAM-ROBBING IN THE CATSKILLS. 505 



The Society reconvened at 2 o'clock p m and listened to the first 

 paper as follows : 



DRAINAGE MODIFICATIONS AND THEIR INTERPRETATION 

 BY M, R, CAMPBELL 



The paper was discussed by W. M. Davis, G. K. Gilbert and the Presi- 

 dent. It is to be published later in the Journal of Geology. 



The next paper was entitled : 



EXAMPLES OF STREAM-ROBBING IN THE CATSKILL MOUNTAINS 



BY N. H. DARTON 



[^Ahstract] 



When we investigate the history of development of drainage systems we often 

 find instances in which a stream has cut through a divide and tapped the head" 

 waters of a neighboring stream, a phenomenon known as stream-robbing. It is 

 accomplished only when there are more favorable conditions of erosion along the 

 stream which does the robbing, usually due to rock texture or attitude, but some- 

 times glacial influences, orographic displacements and chemical erosion are im- 

 portant factors. 



Some of the best marked examples of relatively recent stream-robbing which I 

 have seen are along the eastern face of the Catskill mountains. The two finest of 

 these are the Plaaters kill and Kaaters kill, which have cut back several miles into 

 the mountain and tapped the upper waters of two head branches of Schoharie creek. 

 In plate 23 I have reproduced a portion of the Kaaters kill topographic sheet of the 

 U. S. Geological Survey, which portrays these stream-robbers so plainly that an 

 extended description of them will not be necessary. 



The most conspicuous features of the region are the steep eastern front of the 

 Catskill mountains and the deeply indented gorges of the Kaaters kill and Plaaters 

 kill, all having very precipitous slopes, which are mainly over 1,500 feet in height. 

 The gorges head in high waterfalls and they receive lateral branches, which also 

 descend in falls of greater or less magnitude, of which the Kaaters kill falls are the 

 most noteworthy. Lying above the heads of the gorges, there is an elevated upland 

 containing the wide, gently sloping valleys of the headwaters of Schoharie creek. 

 The divides at the heads of both the Kaaters kill and Plaaters kill gorges have an 

 altitude of very nearly 1,925 feet above sealevel, and they are in saddles which are 

 depressed about 1,600 feet below the summits of adjoining ridges. The former con- 

 tinuity of each branch of the Schoharie depression eastward beyond the present 

 divide at the head of the gorges, is clearly apparent on the map (plate 23), particu- 

 larly in the case of the north branch. From D to ^ a portion of the south side of 

 this depression has been cut away bodily by the invasion of the Kaaters kill gorge, 

 and the waters of the two lakes now pass over Kaaters kill falls at D, while a side 

 branch from the northward passes over Haines falls at E. Some side branches of 

 former Schoharie drainage from the southward now flow down gorges into the 

 Kaaters kill opposite the Kaaters kill falls. The Plaaters kill similarly taps sepa- 



