88 Button— T< rtiary History of Grand Canon District. 



Pliocene. Among them the largest is the Hurricane fault, fol- 

 lowing the west side of the Uinkaret plateau, along which the 

 displacement in the south wall of the Grand Canon is 1500 

 feet; and farther north, near the Virgen Eiver, 6,600. it mak- 

 ing the Hurricane bluff 1200 to 1600 feet— ten miles farther 

 . . tn probal h over I j!.oimi feet, the Eocene being on one side 

 and the Carboniferous on the other— that is, if, as is probable, 

 the.Permian and Mesozoic beds, which there are now absent, 

 were once in the series as they are elsewhere; and. farther 

 north, it extends into Utah, along the west side of the Marka- 

 gunt plateau and the southwest flank of the Tushar range. 

 where it finally ends its course of 200 miles beneath great lava 

 floods. Another is the Kaibab fault which outlines the Kaibab 

 plateau on the west, and extends to the northward about as 

 Ear as the Hurricane fault. The Kaibab fault is referred to the 

 Pliocene and the Hurricane to later Pliocene. 



The numerous volcanic cones and wide spread streams of 

 lavas add greatly to the geological interest of the region. They 

 cover much of the Uinkaret plateau, and descend from it for 

 1500 to 2000 feet into the upper portions of the Grand Canon, 

 and thus prove that the eruptions took place after the great 

 Eaultinc and after a large part of the erosion. But beyond this, 

 some of the streams make a further plunge to the depths of the 

 canon ; and in places over the bottom also there are cones and 

 widely spread sheets of lavas. The Miocene, or its close, was 

 the era of the earlier volcanic out-flows; but a large part were 

 of Pliocene date ; and some are of quite recent time, their 

 scoriaceous lavas looking as if of recent ejection, perhaps dating 

 but a few centuries back. 



In the history of the erosion, Captain Button observes that 

 the first channeling along the line of the Grand Canon occurred 

 in the early Tertiary or at the close of the Cretaceous. The 

 removal of Cretaceous beds that once covered the borders of 

 the Colorado Canon south of the Aquarius plateau, leaving a 

 surface of Jurassi hi Is, ■ is ] irt o{ the earliei erosion The 

 emergence was small in the Eocene, the climate moist, and. 

 during its latter part "the degrading forces no doubt made 

 progress in removing the Mesozoic deposits that origina'ik 

 covered the region;'' and this work wont on throned) the Mio- 

 cene, completing nearly the denudation of the Tertiary. Creta- 

 ceous and Jura-Trias: that is, sweeping off large parts of the.-e 

 upper formations down to the Permian. The cutting of the 

 Grand Canon through the Carboniferous is stated to have gone 

 on after the uplift do-: ,<- p.,. Miocene: at this time "the outer 

 chasm of the Grand Canon was cut 7 ' through the Permian ami 

 the upper part oi the Carboniferous, and although it must at 

 first have been narrow, it finally reached a width of some miles. 



