252 Davis — Notes on the Colorado Canyon District. 



the standard example, best studied, best described, and best 

 illustrated, of river work on a grand scale.* It should be 

 added that the topographical maps made by Bodfish and 

 Renshawe in 1879, although of small scale and large contour 

 interval, are of great value in giving the location and altitude 

 of the more important features. 



The wish that I have had for many years to visit the canyon 

 was fortunately brought to fulfilment in June. Our party 

 consisted of Prof. R. E. Dodge of Columbia University, Dr. 

 H. E. Gregory of Yale University, Mr. R. L. Barrett of Chi- 

 cago, Mr. Richard Wetherill of Pueblo Bonito, New Mex., 

 Dr. Tempest Anderson of York, England, and the writer. 

 Great assistance in plans and outfit was given by Mr. F. E. 

 Hyde, Jr., of New York, who was unhappily unable to go 

 with us. We left the Sante Fe Pacific Railroad at Flagstaff, 

 Arizona, on June -A, and followed a very irregular route north- 

 ward, partly with wagons, partly with horses and pack train, 

 and on June 26 reached Milford, Utah, whence the Oregon 

 Short Line carried us to Salt Lake City. Postponing a fuller 

 account of our observations to a later date, I desire to make 

 brief statement here of certain points on which other conclu- 

 sions than those announced in the Survey reports seem to be 

 admissible. 



The imconformities in the Canyon. — The Kaibab section of 

 the canyon discloses the nearly even floor on which the hori- 

 zontal Paleozoic strata rest. The floor is of complex structure. 

 The fundamental schists with granitic dikes, which are exposed 

 in the western Kaibab section, are overlaid in the eastern sec- 

 tion by the heavy Unkar and Chuar series, dipping eastward 

 and measuring according to Walcott about two miles in thick- 

 ness.f The wedge in which the tilted formations terminate 

 westward is a most remarkable geological structure, alike for 

 its distinctness and for its significance. It is easily recognized 

 near the bottom of the northern cliffs of the canyon when 

 viewed from the southern rim at Hance's or at Cameron and 

 Berry's; these primitive stopping places being at the ends of 

 the road from Flagstaff, which forks a few miles before reach- 

 ing the rim. The wedge is still better seen by descending the 

 Grand Yiew trail from Cameron and Berry's to a promontory 

 of the Red Wall limestone north of the "copper mine." The 

 crystalline floor of the Unkar series is of extraordinary even- 

 ness ; no inequalities in it were detected' in the view from the 

 Red Wall promontory, except a small pre-Paleozoic fault (see 



* Tertiary History of the Grand Canyon District, with Atlas, U. S. Geol. Survey, 

 Monogr. II, Washington, 1882. 



f 14th Ann. Rept, U. S. G. S., 1S94, 508-512. 



