28 THE SALTON SEA. 



is falling at present and as is described elsewhere in this volume by Dr. MaeDougal. It 

 has already been noted that the series of strand-lines formed by Blake Sea and by the 

 Salton can not be distinguished from each other. Blake Sea must be included among 

 very recent phenomena. Its strand lines and terraces are of such character as to fall a 

 ready prey to the elements, even under desert conditions; yet they appear so fresh and 

 undisturbed that any great antiquity is not to be thought of. It is probable that the final 

 disappearance of Blake Sea was less than five hundred years ago, and the entire existence of 

 the water-body can scarcely have been longer. The Indians of the region have a tradition 

 of the previous existence and gradual disappearance of a water-body in the basin, and in 

 spite of the notorious untrustworthiness of Indian legends it seems probable that this one 

 has a basis of truth. Probably some direct evidence, at least of the time required for the 

 disappearance of Blake Sea, could be obtained by a thorough study of its strand-lines, 

 including the accurate determination of their relative elevations. 



If the rise and fall of Blake Sea were due to the accidental entry of the Colorado into 

 a previously existing basin and the later accidental diversion of the river toward the Gulf, 

 there is no reason why this might not have happened many times nor why the basin should 

 not have been often the home of transient lakes, such as Blake Sea seems to have been. 

 Indeed, on a priori grounds such occasional repetitions of the incident would seem very 

 probable. There is, however, absolutely no evidence that any other incursion of the river 

 ever took place. The series of strand-lines of Blake Sea contains no member deeply enough 

 cut to be regarded as marking more than a very transient position of the lake. Nowhere 

 is there any evidence of rise and fall. Nowhere except below the highest level of the present 

 Salton Sea are there any signs of a later series of strands superposed on an earlier. The 

 strand-lines seem to record a continuous and fairly rapid fall of the water-level, and that 

 only. It is possible, of course, that strand-lines, terraces, and similar topographic records 

 of a lake considerably more ancient than Blake Sea might have been entirely destroyed 

 by rain wash during an intervening period, and that earlier lakes might thus have failed 

 to leave any record. It is difficult, however, to see how this could have happened to 

 travertine left by these earlier lakes. If these lakes were similar to Blake Sea and to the 

 present Salton Sea they must have deposited travertine on exposed rocks. It is not likely 

 that such travertine coatings woidd be removed entirely, even by a fairly long subsequent 

 period of erosion. The travertine of Blake Sea would have been deposited on top of these 

 earlier travertines and the present travertine would show a superposition of different 

 travertines, what might be called an unconformity in the travertine layer. Phenomena 

 precisely similar to this are found in the continental lake basins of Nevada and Utah, and 

 are especially well exhibited in the travertines or tufas of Lake Lahontan. Nothing of 

 this sort has been observed in the Cahuilla Basin. Wherever examined the travertines 

 are uniform in character, from the surface of the original rock to the outer layer of the 

 coating; they show no signs of any interruption during their deposition. It is scarcely 

 possible to be dogmatic as to the non-existence of any lakes prior to Blake Sea, but there 

 is certainly no evidence indicating their existence. It would seem that any previous incur- 

 sions of the Colorado must have been so soon checked by natural causes that the lakes 

 produced were small and transient. A lake no larger than the present Salton Sea might 

 fail to leave any record now legible. Indeed the occasional occurrence of such very partial 

 fillings seems probable from the historical records cited by Mr. Sykes on page 15 of this 

 volume. It is a little difficult to understand why the river always returned to its channel 

 after these temporary incursions instead of continuing to fill the basins, as it seems to have 

 done in the case of Blake Sea, and seemed about to do in the case of the present Salton Sea. 



It is perhaps worth while to note the dissimilarity between the history of the Cahuilla 

 Basin and the histories of the superficially similar unchained basins of Nevada, Utah, 

 and eastern California. These latter also have been the home of large lakes now disap- 



