II 



GEOLOGIC PROBLEMS OF THE AQUEDUCT 



INTRODUCTION 



The group of studies assembled in this part are chiefly those that 

 have required considerable exploratory investigation in connec- 

 tion with the proposed Catskill aqueduct and that have furnished 

 new data of a geologic character. In some cases the additional 

 investigations have discovered new and wholly unknown structures 

 or conditions and in all cases the features as now established are 

 much more accurately known than would otherwise have been 

 possible. 



The benefits of the studies have been twofold and reciprocal. 

 On the one side the practical planning of the enterprise has con- 

 stantly required an interpretation of geologic conditions as a guide 

 to locations and methods and on the other the extensive investi- 

 gations carried on have given an opportunity for practical appli- 

 cation of geologic principles under conditions seldom offered and 

 the data secured in additional explorations serve to make the detail 

 of some of these complex features now among the most fully 

 known of their kind. Examples of such cases are (a) the series 

 of buried preglacial gorges (as in the Esopus, and Rondout and 

 Wallkill and ^loodna valleys) and (b) the completed geologic 

 cross sections (such as the Rondout valley, the Peekskill valley, 

 Bryn Mawr, etc.) and (c) the numerous additions to the knowledge 

 of local rock conditions (such as that at Foundry brook, Rondout 

 creek, Coxing kill, Pagenstechers gorge, Sprout brook, and others). 



Almost every locality has its own specific problem and its own 

 peculiar differences of treatment and interpretation of features. 

 Nearly all of the studies here presented came to the attention of 

 the writer and others^ in the form of definite problems or questions 

 involving an interpretation of geologic factors and an application to 

 some engineering requirement. Some of these questions, as is 

 pointed out more fully in part i, chapter 2, are (a) the location of 



1 Professor James F. Kemp of Columbia Universit}- and W. O. Crosby 

 of the Massachusetts Institute of Technology and the writer constituted the 

 regular staff of consulting geologists. 



[75] 



