172 



NEW YORK STATE MUSEUM 



In riding over the Peqnannock catchment several times the 

 writer was much struck by the fact that aside from the main 

 valleys there are no gulleys throughout this area. The record 

 shows that precipitation is frequently very heavy, but it has been 

 thus far without effect. The indications appear to be that the 

 rainfall, however intense it may be, sinks almost entirely into the 

 ground, and without doubt this peculiarity has its effect on the 

 runoff. 



It may be pointed out that the geology of Muskingum and Gen- 

 esee rivers is substantially the same, while the geology of Croton 

 riv^r is entirely different. Nevertheless, when analyzed by aid of 

 the diagrams, these streams are all seen to have substantially the 

 same evaporation and runoff, although the rainfall on Croton 

 river is different from that of Muskingum and Genesee rivers. 

 Hudson river, however, which has much the same geology as Cro- 

 ton river, has still a very different runoff and evaporation. 

 Oswego river, which lies in a different formation from Genesee 

 river, has still nearly the same evaporation. 1 



These several facts favor the view that deforestation is the real 

 cause of the smaller runoff of Muskingum, Genesee, Oswego and 

 Croton rivers. 



Forests 



Do forests increase rainfall? The evidence on this point is con- 

 flicting. The variation of the observed from the true rainfall 

 being so great, as has just been shown, the answer to this question 

 must be regarded as very uncertain. It has been discussed by 

 Professor Abbe and Dr Hough. 2 The following summation by 

 Dr Hough, although made 26 years ago, may be accepted as 

 expressing the fact at the present day. 



The reciprocal influences that operate between woodlands and 

 climate appear to indicate a close relation between them. It is 

 observed that certain consequences follow the clearing off of 

 forests, which can scarcely be otherwise regarded than as a direct 



lThe evaporation of Oswego river is, in fact, a little greater, due to the 

 existence of large marsh areas on Oswego river. 



2Report upon Forestry, by Franklin B. Hough, U. S. Department of Agri- 

 culture (1877). 



