598 PROCEEDINGS OF THE WASHINGTON MEETING 



any direction, I find evidence of what appear to be separate lake basins, covering 

 greater or less areas." * 



A later writer recapitulates his results as follows: 



" Tertiary time in the region of the fortieth parallel is therefore represented by 

 nine lakes — four Eocene lakes, which occupied the middle Cordilleras; . . . 

 two Miocene lakes, one in the province of the plains, the other in western Oregon 

 and western Nevada, and, lastly, the three Pliocene lakes, "f 



Quotations of this kind might be greatly multiplied, until the reader is convinced 

 that during the last forty years it has become habitual to ascribe a lacustrine origin 

 to the Tertiary formations here considered. In the face of these authoritative 

 statements, it is disappointing to discover that no serious investigation of lake de- 

 posits has been published in any of the governmental reports concerning the 

 western Tertiaries. From beginning almost to the end, the assertion has been 

 made, without published critical discussion of the nature of the proof on which it 

 rests. It is well known that an investigation of the kind here alluded to should 

 consist of at least live steps, to enumerate no more. These are : careful observa- 

 tion and generalization of the observed facts, invention or application of an ex- 

 planatory theory, deduction of the legitimate consequences of the theory, impartial 

 comparison of the deduced consequences with the generalized facts, and, finally, 

 judicial consideration of the value of the theory as measured by the degree of 

 accordance between consequences and facts. Some of these steps have been taken 

 in connection with the explanation of the western Tertiaries ; others seem to have 

 been neglected. The facts concerning the formations have been observed in abun- 

 dance; an explanatory theory was introduced to account for the facts, and then, 

 apparently without sufficient attention to the important steps of deduction and 

 comparison, the correctness of the theory was authoritatively announced and widely 

 accepted. The argument for the theory seems to have been about as follows : 

 These Tertiary formations are stratified ; hence they must have been deposited 

 under water. They contain no marine fossils, but an abundance of fresh -water 

 and land fossils; hence the water in which they were laid down could not have 

 been that of the sea, but must have been that of large lakes, whose areas were at 

 least as great as those of the formations now observable. Let us review the ob- 

 served facts. 



Composition op the Fresh-water Tertiary Formations 



The fresh-water Tertiary formations in the Rocky Mountain region consist of a 

 great variety of strata. Some of the strata are of fine texture, even bedding, and 

 constant composition for a considerable thickness, as in the " paper shales" of the 

 Green River basin of Wyoming; others are fine marls of great volume, as in the 

 Eocene of the High plateaus of Utah ; others are clays and very fine sands, as 

 the White River beds of Nebraska; but, in strong contrast to these, there are fre- 

 quently alternating layers of shales and sandstones, as in the central parts of the 

 Vermilion Creek series, north of the Uintah mountains. The same formation con- 

 tains extensive beds of conglomerates, of which the following passages give a vivid 

 idea: 



" West of Concrete plateau there is an enormous development of red sandstone 



* Geological Survey of the Territories, Second Annual Report, pp. 114, 115. 

 f Fortieth Parallel Survey, vol. i, p. 457. 



