ILLUSTRATIONS OF GEOLOGICAL STRUCTURE. 159 



typical examples of "current bedding," sometimes called ''cross- bedding" 

 and "false-bedding," as is abundantly illustrated in the walls of the Hum- 

 boldt, Truckee, and Walker canons. The beautiful curves presented by 

 these irregular beds when seen in section are represented with mucli accu- 

 racy in the detailed sections illustrating the exposures observed. From the 

 thousands of examples examined in various portions of the basin, those 

 presented on Plates XXIII, XXIV, XXV, and XXVII, have been selected 

 as types of this phenomenon. Not only is this structure remarkable for 

 the grace and elegance of the curves produced, but each sweeping line 

 and each curving stratum has an individual structure and varies through 

 all degrees of fineness, and through very many shades and tints, which 

 serve to distinguish it from adjacent deposits. The accuracy of the illustra- 

 tions to which we have directed attention renders farther description of the 

 forms presented by current-bedded gravels when seen in section unneces- 

 sary. 



Examples of what may be properly designated as "drift bedding" are 

 abundant, especially in the walls of the Truckee Canon, which furnish fine 

 examples of the oblique stratification produced when currents sweep sand 

 and gravel along the bottom until the edge of a scarp is reached and then 

 deposit them in inclined layers. Under favorable circumstances this action 

 may continue until a stratum is formed that is obliquely stratified from top 

 to bottom, perhaps several feet in thickness, and of wide extent, as illus- 

 trated in the central portion of the section exposed in the Truckee Cailon. 



Tlie deposition of current-borne debris in inclined strata sometimes 

 takes place on a grand scale, as is illustrated by the section of the gravel 

 deposits at the southern end of Humboldt Lake, shown in Fig. 17, and 

 again by Fig. 20, which represents a section of a similar structure at the 

 southern end of Winnemucca Lake. In the canon of the Walker River, 

 evenly-bedded strata inclined at an angle of from 15° to 20° are exposed 

 in a section that is fully 200 feet high, as represented on Plate XXVIII. 

 In all these examples, and in many others that have been studied, the 

 current-borne gravels composing the strata were deposited in the inclined 

 position they now occupy, and do not owe their inclination to a movement 

 of the beds subsequent to their deposition. Stratified beds deposited at an 



