882 W. LINDGREN~F. H. KNOWLTON 



Survey by Messrs. Turner and Diller and myself, the auriferous 

 gravels have been indicated as "Neocene," including under this 

 name the Miocene and the Pliocene. The same authors have 

 correlated the lacustrine or brackish lone formation along the 

 western base of the Sierra with the fluviatile auriferous gravels 

 on the flank of the range, and the two former authors have con- 

 sidered the age of both as probably Miocene,' basing their con- 

 clusions upon the more recent palaeobotanical determinations of 

 Professors Leo Lesquereux, Lester F.Ward, and F. H. Knowlton. 

 Recently Professor Lawson^ accepts Professor Whitney's deter- 

 mination of the auriferous gravels as Pliocene and thinks that 

 the determination of the eroded surface on which rest the 

 lone formation and the auriferous gravels, as Miocene, may be 

 in need of revision. 



STRATIGRAPHIC RELATIONS OF THE AURIFEROUS GRAVELS. 



The investigations of the United States Geological Survey 

 have fully confirmed the earlier results as to the fluviatile char- 

 acter of the auriferous gravels over the whole flank of the 

 Sierra Nevada above an elevation of a few hundred feet above 

 the present sea level. Along the western base and at the 

 northern end the auriferous gravels merge into brackish and 

 lacustrine deposits. Along the western base the latter have been 

 but little disturbed, while, according to Mr. Diller, they have 

 experienced a considerable elevation at the northern end of the 

 range. In a former publication 3 I have indicated the direction 

 and the grade of the channels over a part of the western slope 

 and investigated the character of the surface on which the 

 gravels rest. The surface is that of a gently sloping, greatly 

 eroded mountain range, but by no means reduced to a base level 

 and not even to be considered as a peneplain. Only on the 



'8th Ann. Report U. S. Geol. Survey, p. 420. 

 14th " " " " " p. 466. 



14th " " " " " p. 423. 



American Geologist, Vol. XV, June 1895, p. 375. 



2 Bull. Dep. Geol., Univ. Calif., Vol. I, No. 4, p. 157. 



3 Bull. Geol. Sci. Am., Vol IV, p. 270. 



