CERTAIN TYPES OF STREAM VALLEYS AND THEIR 



MEANING 



JOHN LYON RICH 



University of Illinois, Urbana, 111. 



A recent study of the ''thalwegs" or immediate valleys of a 

 number of streams, with particular reference to their ground-plan 

 and their form as revealed in cross-section, has brought to my 

 attention a wide difference in form of valleys produced by different 

 streams and even by a single stream in different parts of its course. 

 A subsequent failure to find in the literature any approximately 

 complete explanation of these differences in form leads me to 

 attempt the following analysis of the work of a river in carving its 

 valley, in the hope that it will lead to a clearer understanding of 

 the meaning of these marked morphological differences and will 

 pave the way for the use of these distinctive valley forms as criteria 

 for the interpretation of the physical history of a region where they 

 occur. 



An examination of a large number of valleys, as delineated on 

 the contour maps pubHshed by the United States Geological Sur- 

 vey and by the French and German Surveys, led to their classifica- 

 tion under three types which seem fundamental. For each type 

 there is a further series of stages marking the development of the 

 valley from its initial to its final form. For the three types I sug- 

 gest the following names: 



1. The Open Valley. 



2. The Intrenched Meander Valley. 



3. The In-grown Meander Valley. 



The Open Valley is one which is either straight, as valleys go, or 

 winding in broad, open curves. The valley sides are relatively 

 straight and may be smoothly trimmed. The stream swings from 

 side to side in broad, open curves which, except in the very earliest 

 stages, do not necessarily correspond with the curves of the valley 

 as a whole. 



