DERIVATION OF THE NAME " CINNABAR." 351 



lovvstoiie river flows through a narrow valley, iu which Cinnabar mountain 

 is a small but conspicuous topographic feature, through Yankee Jim canon 

 to the broad mountain-encircled Paradise valley, and thence onward through 

 the Gate of the Mountains to the terraced valley about Livingston, where it 

 begins its long wanderings through the plains of Montaua. 



The Cinnabar coal field takes its name from Cinnabar mountain, a low 

 mass of upturned strata exposing a fine section of the geological series 

 from the Archean to the coal-measures of later Cretaceous age. The title of 

 the mountain is a misnomer, however, since the bright red streak forming 

 so prominent a feature in its structure is a band of red sandstone, probably of 

 Triassic age. 



General Geology. — On the western side of the valley the coal-bearing 

 strata form a high and flat-topped mountain ridge, extending down from 

 the sharp and rugged summit of Electric peak, the highest point in the 

 region, and ending in the upturned strata of Cinnabar mountain. North 

 of this block of Cretaceous coal-bearing strata there is an extensive area of 

 volcanic rocks that form the rugged mountain peaks of the Gallatin range, 

 and consist of breccias of fragmental volcanic ejectamenta, together with 

 numerous flows of andesite and basalt. A fault, whose line corresponds very 

 nearly with the course of Cinnabar creek, brings the sandstones of the coal- 

 bearing strata directly against these volcanic rocks. 



On the east an equally profound fault separates the sedimentary beds from 

 the breccias forming Sepulchre mountain — a rugged mass of lava which lies 

 between the coal-bearing rocks of Electric peak and those within the Yellow- 

 stone National Park which form Mount Evarts. 



On the eastern side of the valley the steep slopes of Sheep mountain 

 rise abruptly from the river, and the gneisses and granite extend eastward 

 beneath the volcanic breccias, which form a series of snowy mountain peaks. 

 In the upper or southern portion of the valley, a narrow block of coal- 

 bearing rocks is found on the northeastern side of the Yellowstone river, the 

 beds dipping steeply toward a fault which separates them from the gneisses 

 toward the north. They are capped by a sheet of basalt, which is in turn 

 overlain by very extensive deposits of hot-spring limestone or travertine, 

 formed by springs of which no other traces now remain. 



The Mesozoic Section. — In the upturned beds of Cinnabar mountain may 

 be seen a section giving the relations of the Cinnabar coals to the older rocks. 

 Resting upon metamorphic gneisses there lies about 2,500 feet of limestone, 

 the upper portion containing Carboniferous fossils. The beds are vertical, 

 but are so crushed that the Carboniferous, Devonian, Silurian, and Cam- 

 brian strata are not readily separated. Above these limestones there is an 

 arenaceous zone, overlain by the vermilion-red sandstone forming the Devil's 



