128 FouKTH Annual Report of the 



lilies of weakness along which secondary erosion and valley widen- 

 ing take place. Abrupt ledges are frequent and are often a 

 source of great difficulty in ascending a peak by unsual paths. 

 To the vertical jointing and erosion along the joints is also to be 

 attributed the successive steps which are common features of the 

 valley floors and give rise to numerous picturesque cascades. 

 (See Plate No. IV.) 



Although the Catskills were overridden by pleistocene ice, signs 

 of which are everywhere abundant, the ice appears not to have 

 had any important effect upon the topography; rather, it con- 

 formed to the broad slopes, only slightly moulding them here and 

 there by the deposition of small quantities of glacial till or by the 

 erosion of the sharper forms. 



The soil consists of a stony sheet of glacial till composed for 

 the most part of a sandy loam. In the valleys and on the lower 

 slopes it is of good depth, but becomes very shallow on the upper 

 slopes and ridges. Places are to be seen where the surface of 

 the ground is covered to a depth of several feet with large 

 boulders, the only soil being a slight accumulation of decaying 

 leaves and other debris. While in these places no water is ever 

 found on the surface, it can often be heard running through the 

 rocks a few feet below. Practically none of the land on the area 

 described is of such a character that it could ever be used for 

 agricultural purposes. 



In the forest cover the following types have been recognized 

 characterized by differences of topogTaphy and composition of the 

 stand : 



(1) The slope type comprises the area along the small streams 

 and extends up the hillsides to the steeper slopes where a cihange 

 to a certain extent in composition, but mainly in the form and 

 height of the trees, becomes very marked. (See height tables for 

 slope type and ridge type.) 



The most noticeable change in composition is the dropping out 

 of such species as basswood, white ash and hemlock as one begins 

 to ascend the steeper slopes and the prescence of balsam fir and 

 black cherry on the upper slopes and ridges. 



The heaviest stands and best timber are necessarily found on 

 the lower slopes where the deeper soil affords a more abundant 

 supply of moisture and plant food elements. On the lower slopes 



