THE BASIN PROVINCE 125 



equivalent, for these belong entirely upon the eastern side of the Rocky- 

 Mountain barrier within the Plains Province. Aside from the remote 

 possibility of an arm or extension of the depositional area from the Plains 

 Province to the west across the barrier in this locality, the probability is 

 that these red beds are an extension of the Rio Arriba Beds (New Mexico) 

 and Cutler Beds (southwestern Colorado) to the north. 



Beyond the limits of southwestern and western Colorado, to the west 

 and northwest, the red beds cease to appear in their characteristic develop- 

 ment, but the deposit of the equivalent period seems rather to be changed 

 in character than to be absent from the geological column. To realize the 

 geographical continuation of the upper Pennsylvanian surface which marks 

 the beginning of the Permo-Carboniferous series it is most convenient to 

 trace the position of the Weber quartzite, already fixed in its relations to 

 the Hueco limestone of the Guadalupe Mountains. The Weber quartzite or 

 sandstone, which is one of the most widely distributed and easily distin- 

 guished horizons of the Pennsylvanian, is said by Hague to stretch all the 

 way from the Front Range in Colorado to the Eureka Mountains and can 

 be traced north, to southern Wyoming. 



{e) Conditions in Nevada. — In the Eureka area, according to Hague, the 

 Weber is overlain by 500 feet of upper Pennsylvanian limestone, but its 

 thickness has been reduced by erosion. In the northern and central portions 

 of the State the beds are 2,000 feet thick. They are distinguished by their 

 light color and the prevalence of fine-grained beds. "These colors are light 

 bluish-gray and drab, the latter possessing a conchoidal fracture and compact 

 texture. * * * Throughout the horizon the limestones are interstratified with 

 belts of grit and siliceous pebbles, held together by a calcareous cement, in 

 which are intercalated thin beds of purer limestone." These limestones are 

 very free from MgCOg, the only Paleozoic horizon at Eureka free from dolom- 

 itic strata. 



A similar condition seems to be traceable to the northwest, where at 

 Battle Mountain, Nevada, HilP reports the following conditions: 



''Limestones. — The limestones are well exposed on Antler Peak, and a small 

 area underlain by these rocks occurs west of the rhyolite cap rock at the east 

 side of the mountains west-southwest of Battle Mountain. Of the limestones of 

 Antler Peak the Fortieth Parallel geologists say : ' They extend from the summit to 

 the very bottom of Willow Canyon * * *, exposing 1,200 feet of heavily bedded, 

 dark-gray limestones in places somewhat shaly and of light bluish-gray tints. 



"Carboniferous fossils were found near the base and 100 feet below the 

 summit of these beds. 



"The writer collected some fossils from the limestones exposed on the east- 

 west ridge at a point 7 miles west of Battle Mountain, under the rhyolite cap. 



^ Hill, James M., Some Mining Districts in Northeastern California and Northwestern 

 Nevada, U. S. Geological Survey Bull. 594, p. 66, 1915. 



