TTPPEK (}l ATKRNAKY. 33 



yon, these upper Quateniiirv acciinmlatioiis cxtciul up the Hauks of the 

 mountains for 1,500 feet al)()ve tlie lowest jjart of Fish Creek VaUev, every- 

 where concealing' the nature of the underlying- rocks. 



Most of the ijitervenino- meridional valleys lying l)et\veen the parallel 

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

 son with the level })lains bordering the Eureka Alountains. In western 

 Utah and eastern Nevada these valleys exhiV)it great similarity as regards 

 their physical and geological history. They have been desci-ibed at great 

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

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

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

 of these valleys may also be found in the volume deAa)ted to thedescriptive 

 geology of the Fortieth Paralhd Exploration,^ and the reader who desires 

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



' U. S. Gcol. Exjilor. of the Fortieth Parallel, vol. i. Systematic C4ooIo','.V- 



= U. S. Gcol. Surv., Sloiiograph I. Lake lionncville. 



^U. S. Geol. Explor. of the Fortieth I'aralkl, vol. il. Iteseriptivc Geoloj;y. 



MON XX 3 



