86 Button— Tertiary History of Grand Canon District 



its profiles are perfectly 

 high, descends vertically 



ceciK'<i by a steep slope of ever- u idening base-course^ I, -a- 1 ing down 

 To the esplanade below. The curtain wall is deeoiati d with a lav- 

 ish display of vertical mouldings, and the ridges, eaves, and mitred 



The illustrations of the report, both in the text and atlas, are 

 admirable, and more than sustain the author's descriptions. 

 Those from the drawings of Mr. Holmes are like photographs 

 in accuracy of detail and aerial effect. Plate IV is a reduced 

 copy of a plate in the text, representing " Vishnu's Temple. 

 one of the architectural masses in the Canon south of the 

 Kaibab plateau, havinj u //<./<//// /,-,,■,-,} //> base of 5500 feet. For 

 others, and a continuation ot the descriptions'of this region of 

 nature's architectural marvels, the reader is referred to the 

 report itself. 



The following are some points in the geological history oi 

 the region which the report brings out: 



While Silurian and Devonian rocks (the latter paleontologi- 

 cally identified in the Kanab Canon by Mr. Walcoti) occa- 

 sionally occur, the Carboniferous, for the most part, rests 

 directly on the Archaean. Between the Carboniferous and the 

 underlying Paleozoic beds there is always uneonformubiliiy, 

 both through the greater or less dip of the latter and the ero- 

 sion of the surface; and the same is true through the Sierra 

 country of central and western Arizona, and of Nevada and 

 western Utah. But from the bottom of the Carboniferous to 

 the top of the Cretaceous the beds are one continuous conform- 

 able series. The beds of this long range appear to have been 

 deposited horizontally ; the thick lower limestone of the Car- 

 • a- probably made in moderately deep water, and 

 the rest of the formations— most! v sandstones and shales- near 

 mean-tide level, as proved bv Yipple-marks and other evi- 

 dences. From this fact is drawn the important conclusion that 

 a gradual subsidence was taking place as the depositions went 

 forward: and since the Cretaceous contains lignitic or coal- 

 bearing beds throughout, and at short intervals' alternating in 

 the upper part with brackish-water instead of marine beds, it 

 is inferred that there \ 



going on during its progress also, ending finally 



