64 



SCIENCE. 



[Vol. IV., No. 76. 



Cope. At the end of the eocene, this lake 

 was drained \>y elevation, the present river- 

 system was established, and the general erosion 

 commenced. It is probable, that, during the 

 miocene, the climate was moist, the rain ex- 

 cessive, and the general erosion very great. 

 Most of the general erosion was done during 

 this time. During the pliocene the elevation 

 was greatly increased, the climate became diy, 



certainty in this Capt. Dutton excels. We 

 would especially draw attention to his realty 

 magnificent description of the towers of Vermil- 

 ion Cliffs (p. 86), of the temples and towers of 

 Virgen River (p. 88), and his ride on Kaibab 

 plateau to Grand Canon (p. 136). 



It is needless to say that the memoir is illus- 

 trated in a manner worthy of the subject. 



It is already well known, through the previous 



and, while a moderate general erosion con- 

 tinued, the stream-cutting became excessive. 

 The upper, outer, and greater part of the Grand 

 Canon was made at this time (see the accom- 

 panying figure). Toward the end of the plio- 

 cene, things settled for a while : the streams 

 reached a base-level, and cut no deeper for a 

 long time. At the beginning of the quaternary, 

 a somewhat rapid rising again began, and has 

 continued to the present time. This last rising 

 inaugurated the cutting of the inner canon. 

 The comparatively rapid rising of the pliocene 

 and quaternar}^ times produced the north and 

 south faults, and, in connection with these, 

 igneous outbursts on a grand scale. 



Although the author does not, ive would 

 correlate this last elevation and its outbursts 

 with the elevation and lava-flows which took 

 place in California at the beginning of the 

 quaternar} T , and the inner canon of the Colo- 

 rado with the deep canons of the present river- 

 systems of that state. In middle California 

 the pliocene rivers were displaced b} T the lava- 

 flows, and therefore had to cut new beds. 

 These were cut much deeper than the old, 

 because the country was greatly elevated at 

 that time. But in southern California the 

 country was elevated, but the rivers were not 

 displaced : therefore, like the Colorado, they 

 cut in the same place, but deeper ; and rem- 

 nants of the old beds are now found on the 

 flanks of the present canons. 



Capt. Dutton has sometimes been criticised 

 for a style unbecoming a scientific treatise. 

 We do not agree with these critics. Nothing 

 short of vivid word-painting can give an}- 

 adequate idea of the peculiar scenery ; and 



labors of Gilbert and King, that in quaternary 

 times the basin region was largely occupied 

 by two great lakes, separated by the East 

 Humboldt Range. The one occupying Utah 

 basin, of which Great Salt Lake, Utah, Bear, 

 and Sevier Lakes are the residues, was named 

 by Gilbert, Lake Bonneville ; while that occu- 

 P3 T ing Nevada basin, and of which Pyramid, 

 Winnemucca, Carson, Humboldt, and Walker 

 Lakes are the residues, was named by Mr. 

 King, Lake Lahontan. The complete study of 

 these lakes has been undertaken by Mr. Gilbert 

 and Mr. Russell. The great importance of this 

 investigation lies in the fact that lakes without- 

 outlets are the clearest indicators of changing 

 climate. We can onty touch lightly the most 

 important results, referring the reader to the 

 memoir for the proofs. 



According to King, in early pliocene a great 

 lake, which he calls Lake Shoshone, covered 

 nearly the whole basin region . This lake seems 

 to have dried away almost completely by the 

 end of the pliocene. At this point Gilbert takes 

 up the history of the region. At the end of the 

 pliocene, Utah basin had a dry climate and a 

 small residuary lake, as at present. During the 

 quaternarj^, the lake rose until it reached a level 

 nine hundred feet above the present, but did 

 not find an outlet. Then it dried away grad- 

 ually and probably completely, and its residual 

 salt was buried beneath fine clay, or ' playa 

 deposits ' of Mr. Russell. This was followed 

 b} r a second rising, which reached still higher, 

 and the lake found an outlet into the Snake 

 River. The lake was therefore fresh. The 

 outlet stream cut its way down three hundred 

 feet or more, until, finding a hard limestone, the 



