CENTRAL AND EASTEEN NEVADA. 413 



to 25° west of north, and dip westerly at an angle of 26° to 28°. Upon 

 Babylon Hill they maintain the same dip, but strike from 35° to 40° west of 

 north. Nowhere, within the limits of the district, do the beds underlying 

 this formation of limestone appear at the surface. We have, therefore, no 

 means of knowing its thickness. There is, however, at least 1,500 feet of 

 strata exposed. The uppermost beds of limestone are highly fossiliferous. 

 The fossils obtained place the age of the formation without doubt in the De- 

 vonian period. The limestone is of a bluish-gray color, hard and compact. 

 Near the ore-bodies, where subjected to the same chemical action which pro- 

 duced the metalliferous deposits, it is highly impregnated with foreign mat- 

 ter, particularly with silica; but where removed from such action, it is re- 

 markably pure. 



A limestone specimen, taken from the east bluff of Treasure Hill, has 

 been analyzed by Mr. 0. D. Allen, of the Sheffield Laboratory, Yale College, 

 with the following result : 



Lime 55.38 



Magnesia .25 



Carbonic acid 43. 70 



Insoluble residue .70 



100. 03 



The insoluble residue contained a little iron. 



Immediately overlying the Devonian limestone occurs a formation of 

 thinly laminated calcareous shale. The color of the shale is dark-gray ; many 

 of the beds, however, are interstratified with thin, reddish-gray bands, alter- 

 nating with those of a dark-gray color. This shale has been eroded ojBf from 

 the greater part of Treasure Hill. It is found, however, on the depression 

 between Treasure and Telegraph Peaks; underlies the summit of the latter 

 point, and may be traced for quite a distance along the western slope of the 

 hill, dipping conformably with the limestone. Its thickness may be best de- 

 termined upon the east side of Treasure Hill, immediately above Applegarth 

 Canon, where it is about 125 feet. The calcareous shales, as far as yet known 

 are entirely nou-fossiliferous. 



