Certain Types of Stream Valleys and Their Meaning

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 published by the United States Geological Survey and by the French and German Surveys, led to their classification 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 suggest the following names: