94 
MUSEUM BULLETIN NO. 2. 
be referable to the Albertella fauna, a zone which appears to 
occupy a debatable position between the Lower and the Middle 
Cambrian, is fortuitous and it will be necessary to preface the 
discussion of the age of the Burton formation by a general review 
of our present knowledge concerning the Albertella fauna, the 
Pioche formation, the relations of the basal Cambrian to the 
Pre-Cambrian rocks, and the boundary between the Lower and 
the Middle Cambrian in the Cordilleran region. 
THE BASAL CAMBRIAN AND ITS RELATIONS TO THE 
PRE-CAMBRIAN. 
The formations referred to the Pre-Cambrian in the Cordil- 
leran region have already been described and correlated in 
detail. 1 In this review Schofield 2 has outlined the diastrophic 
criteria for the separation of the Burton formation (Cambrian) 
and the Roosville (Pre-Cambrian). In the following pages will 
be given a fairly detailed account, mainly from a palseontologic 
standpoint, of the beds composing the basal Cambrian in the 
various districts and of their relations to the Pre-Cambrian. 
Of the sections described the writer has visited those in 
British Columbia, Idaho, and Utah, with the single exception of 
the one at Yellowhead pass, and has drawn largely upon his 
unpublished field notes for the data which follow. 
The various districts are arranged in an order comparable 
with the successive stages in the advance of the Lower-Middle 
Cambrian sea upon the Cordilleran region, as follows: Cali- 
fornia, Nevada, Arizona, Utah, Idaho, Montana, and British 
Columbia. 
California, Inyo County, Waucoba Springs . — The Lower 
Cambrian occurs east of Waucoba Springs, on the Saline Valley 
road, east of the Inyo range, Inyo county, California, 3 as a 
series of limestones, arenaceous limestones, shales, and sand- 
stones, 5,670 feet thick, without observed upper or lower 
limits, and within which the genus Olenellus and its immediate 
Schofield, S. J.: Geol. Surv., Can., Museum Bull. No. 2, pp. 79-91. 
2 Idem, p. 84. 
3 Walcott: Smithsonian Misc. Coll., vol. 53, No. 5, 1908, pp. 185-188. 
