82 Button — Tertiary History of (inmil CoTton District. 



various canons of the district, their excavation, and the origin 

 of special details. 



In a previous Eeport on the High Plateau IHstrici of Utah, 

 published in 1880, Captain Dutton had described with like 

 fulness the country immediately north,* and the two Reports 

 relate really to different parts of the same great plat(;au area. 

 Between the parallels of 40° and 40° 30', the Great Salt Lake 

 comes to its southern end. Just east, in the same latitude, the 

 Wasatch Mountains, rising in points to 13,000 feet, begin their 

 ->n\\\\ course. Farther eastward are spread out the 

 tamer Uinta Mountains, a great plateau, 150 miles from east 

 to west, and averaging lu.d'OO to 11,000 feet in height, yet 

 reaching at one place a height of 13,694 feet. To the south. 

 below the parallel of 40°, the W; if into the 



"High Plateaus" of Southern Utah, the Wasatch, Pavant. 

 Awapa, Aquarius, Paunsagunt an i M i igm t \ (trans, rang- 

 ing from 10,000 to 11,600 feet in height, which are the subject 

 of the former Report. These plateaus have together a length 

 from north to south of 175 miles, with a breadth of 25 to 80 

 miles. Eocene beds, of lacustrine origin, are widely distribute! 



basaltic lavas of still later origin; and Cretaceous. Jurassic. 

 Triassie, Permian and Carboniferous rocks come to view suc- 

 cessively on descending into the intersecting gorges or valleys. 



Passing south and southeast of the southernmost of these 

 High Plateaus, the Markagunt and the Paunsagunt. a series of 

 pa commences leading down, over successive cliffs and 

 broad plateaus, from the Eocene table-land of the summit to, 

 finally, the depths of the Grand Canon — and with the account 

 of this majestic " stairway" the new Report begins. 



These successive steps to the caiion, along with the plateaus 

 below them, cover a region on the north side of the river 

 averaging 75 miles in breadth. The plateaus which this border 

 area of the Grand Ca rjg to tl e eastward, 



are the Kaiparowits, Paria, Kaibab, Kanab, Uinkaret, and 

 Sheavuits plateaus. 



The first step down from the Eocene of the summit is over 

 Cretaceous roeks, for 4000 to 5000 feet — a vast series of sand- 

 stones and shales, of pale yellow ami li-ht brown t<> ^ra\ 

 hades, rather brilliant in effect. The Kaiparowits phrVau', the 



easternmost, is wholly Cretaceous at 



nd similar Ovt.-,, 



parowits pi 



of the Colorado; and similar Cretaceous mesas cover nearlv 



stern Arizona and reach indefinitely eastward. The 



n downward is over the Jura-Trias— first a descent 



of 300-500 feet over red shales with 1, ^ihfcron^ calcareous 



layers containing Jurassic fossils; then a great stratum of 



