UPPER QUATERNARY. 33 



yon, these upper Quaternary accumulations extend up the flanks of the 

 mountains for 1,500 feet above the lowest part of Fish Creek Valley, every- 

 where concealing- the nature of the underlying rocks. 



Most of the intervening meridional valleys lying between the parallel 

 ranges of Nevada consist of narrow, trough-like depressions, in compaii- 

 son with the level plains bordering the Eureka Mountains. In western 

 Utah and eastern Nevada these valleys exhibit great similarity as regards 

 their physical and geological history. They have been described at great 

 length by Mr. Clarence King 1 and Mr. G. K. Gilbert, 2 both of whom have de- 

 voted much time to the study of the Quaternary accumulations and the cli- 

 matic conditions under which the material was laid down. Many local details 

 of these valleys may also be found in the volume devoted to the descriptive 

 geology of the Fortieth Parallel Exploration, 3 and the reader who desires 

 to pursue the subject further is referred to the works quoted. 



1 U. S. Geol. Explor. of the Fortieth Parallel, vol. I. Systematic Geology. 



2 U. S. Geol. Surv., Monograph I. Lake Bonneville. 



3 U. S. Geol. Explor. of the Fortieth Parallel, vol. n. Descriptive Geology. 



5ION 



