RIVER TERRACES AND REVERSED DRAINAGE 



675 



proportional to a given stream flow, and when not interfered with 

 will gradually bring itself to maturity, then the down-sweeping 

 of an unobstructed meander must eventually result in its collapse 

 and self-destruction through the medium of a cut-off. The 

 present Catatonk River has obsolete meanders, now represented 

 by more or less filled in cut-offs, or miniature oxbow lakes, that 











Fig. 3. — Terraces along Catatonk River, N. Y. 



seem to gauge the limit of its radius in meander development. 

 The full extent of its present mature meanders and the shifting 

 of the meander belt is much less than the opportunity offered 

 by the flat bottom plain extending across the valley. 



To whatever state of maturity the valley development had 

 attained preglacially, it was directly modified by the advent of 

 the glacial epoch. The old valley floor and its grade must have 

 been somewhat affected by the southward movement and erosion 

 of the first ice advance, and a probable lowering of the pre- 

 glacial divide. Upon a subsequent retreat of the ice it was 



