100 



INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



On the north side of Silver Canyon, No. 3 is well exposed and is estimated to have a thick- 

 ness of 2,000 feet. Above this a series of limestones and calcareous and siliceous shales 

 occurs and some interbedded dark quartzitic sandstones, that extend upward 1,000 feet. Near 

 the base a massive-bedded limestone 100 feet in thickness occurs, in which great quantities of 

 Lower Cambrian corals (Archseocyathinse) occur. This series is capped by about 200 feet of 

 compact thin-bedded arenaceous argillite, with interbedded layers of dark-brown fine-grained 

 quartzite. 



The entire section, briefly summarized from summit downward, is as foUows: 



•^ ' Feet. 



4. Upper arenaceous beds 200 



3. Alternating limestones and shales 1,000 



2. Siliceous slates and quartzites 2,000 



1. Siliceous limestones 1,700 



4,900 



In round numbers the section exposed in the White Mountain Range, between White Moun- 

 tain Peak and Waucobi Canyon, is 5,000 feet in thickness. 



No fossils were found in the lower limestone. Numerous annelid trails occur in the lower 

 sUiceous series, and in the slaty portion near the summit heads of OleneUus were found. In 

 places the lower portion of the upper limestone series is almost a solid bed of different forms 

 of the Archseocyathinse. EthmopJiyllum whitneyi Meek is very abundant, and the genera Pro- 

 topharetra, Coscinocyathus, and probably Archseocyathus occur. EthmophyUum ranges 

 throughout the limestone series into the base of the shales in ToUgate Canyon, where it is asso- 

 ciated with cystidean plates and fragments of OleneUus. On the north side of Silver Canyon 

 the Archseocyathinse are so abundant in the limestone that it may practically be called a Lower 

 Cambrian coral reef. This reef was traced for nearly 30 miles, and the same types are also 

 known to occur in the Silver Peak Range, about 25 miles to the eastward. 



So far as known to me, this is the oldest of the Cambrian faunas known in the western 

 portion of the United States. Just what its relations to the OleneUus fauna of central Nevada 

 and British Columbia are I am unable at present to state, except that I believe it to be older 

 than the OleneUus fauna of central Nevada. 



It is not impossible that a fauna will be found in the lower limestone, but in the hasty 

 reconnaissance in which I was engaged only a portion of one day was given to the examination 

 and measurement of the section. I hope in the future to extend the study of the Wliite Mountain 

 Range, as Mr. Fairbanks has written me that he has discovered Fusilina cylindrica in the southern 

 end of the range, east of Keeler, which is about 50 miles south of ToUgate Canyon. If the 

 section is unbroken, the Middle and Upper Cambrian and Ordovician faunas should be found 

 before reaching the Carboniferous horizon discovered by Mr. Fairbanks. 



In recent papers Walcott^" has supplemented the data regarding the earliest 

 Cambrian stratigraphy and faunas as follows : 



The oldest known Cambrian fossUs are found deep down in the Lower Cambrian strata 

 of southwestern Nevada and the adjoining Inyo County area of eastern California. In sections 

 120 miles apart the Lower Cambrian has a thickness of over 5,000 feet, with a great limestone 

 forming the upper 700 to 2,000 feet. Below this limestone calcareous strata occur, but the 

 predominating rocks are sandstones and arenaceous, siliceous, and calcareous shales. In the 

 lower 400 feet of the Waucoba Springs section and the Barrel Spring section south of Silver 

 Peak in western Nevada the fauna includes — 



Annelid trails. 

 Protopharetra sp. undt. 

 Archaeocyathus sp. undt. 

 EthmophyUum cf. whitneyi Meek. 

 Mickwitzia occidens Walcott. 



Trematobolua excelsis Walcott. 

 Obolella sp. undt. 

 Orthotheca sp. undt. 

 Holmia rowei n. sp. 

 Holmia weeksi n. sp. 



