PHYSICAL AND CLIMATIC SETTING 13 



from the network of valleys that have been formed 

 in its structure. While these broad valleys traverse 

 the region in all directions, the prevailing one is 

 north and south. They are continuous from one 

 drainage system to the next and consequently form a 

 system of deep passes, called Through valleys, that are 

 the thoroughfares of modern travel. The Catskill 

 portion being the highest, is most broken and has little 

 agricultural importance. It occupies about a sixth of 

 the area. The main plateau has a maximum eleva- 

 tion of 1800 to 2500 feet and is bounded on the north 

 by about the 1000 foot contour. 



The valleys, especially the north-south ones, have 

 two main slopes : first, the interior, rather steep walled 

 that bound the narrow valleys of alluvial and terrace 

 land, usually of good agricultural value; second, the 

 upper slope which forms a broad, moderately graded, 

 U-shaped trough. Over most of these slopes, mod- 

 ern machinery may be used readily. 



These distinctions in topography should be kept 

 clearly in mind since they are essential to a correct 

 appreciation of the agricultural and industrial de- 

 velopment of the region later to be discussed. 



A large part of the southern area is tillable land, 

 especially that associated with good valleys, bearing 

 prosperous farms. However, it is within this as 

 well as the other highland areas, that the margin of 

 profitable farming is most frequent and in which the 

 shifts of economic pressure have had their most 

 marked effects. 



