JOHN WESI.KY 1'OWKU. DAVIS 



Attention to stream action naturally led to an attempt to 

 classify streams and valleys. Two classifications were pro- 

 posed; the first was based on the relation of streams to the 

 strata that they traversed ; several types were admirably illus- 

 trated in ideal figures drawn by Holmes, and each type was 

 given a name of Greek origin, as cataclinal, diaclinal, and so 

 on; but these names have not come into general use, perhaps 

 because they express only an empirical relation. The second 

 classification of streams and valleys was in terms of their 

 origin ; the three kinds here recognized were given names of 

 Latin derivation antecedent, consequent, and superimposed 

 last two kinds having been recognized but not named by Mar- 

 vine, from whom Powell quotes; and these names have come 

 into general use among modern physiographers. River be- 

 havior was discussed with much originality, and reasonable 

 meaning was given to features that had previously been stated 

 empirically; for example: "In the Colorado river, with very 

 few exceptions, all the falls and rapids which beset its course 

 through the great canons are caused by dams of boulders 

 made by side streams having great declivity" (Uinta, 193). 

 Regarding Platte River, on the plains, it is luminously stated: 

 "The beds through which the river runs are incoherent, and 

 although the river has as great a fall as the Colorado through 

 the plateaus, and although the climatic conditions are essen- 

 tially the same, yet the former runs in a broad sheet scarcely 

 below the level of the plain, while the latter runs in a narrow 

 groove at profound depths below the general surface" (Uinta, 

 194). The nature and amount of river load and the manner 

 of its transportation are carefully considered. The load "does 

 not float on the water, but behaves as an integral part of it, 

 and with ft obeys the laws of hydrodynamics" (Uinta, 184). 

 The principles here announced were afterwards developed with 

 greater fullness in an address before the National Academy 

 of Sciences, under the title of '"The laws of hydraulic degra- 

 dation," with the object of mentioning "the principal efficient 

 methods of controlling rivers in their floodplain reaches;" 

 and here Powell's indifference to precedent is shown again, 

 for although the problem and the technique of river control 

 have been abundantly discussed and successfully practiced in 



