80 



GRAND CANON DISTRICT. 



Province. The Great Basin was then dry land, undergoing denudation, 

 and its detritus was washed down on this side into the sea, where the 

 Mesozoic strata of the Plateau Province accumulated. The position of 



this ancient shoreline in the Sierra country south of the Great Basin 

 and west of the Grand Gafion district we do not as yet know; the pre- 

 sumed location not being explored as yet. This attenuation of the 

 strata and their relation to the shoreline of the mainland, from which 

 they were in great part at least derived, is another important factor 

 which must be kept in mind in the course of the discussion. 



It will be well to bestow also a glance at the distribution of the more 

 important drainage channels. The western portion of the terraces is 



Fig 5.— Eutraucc to the Pani-nu-weap. 



drained by the branches of the Virgen River. Upon the Colob heads 

 the northern fork of the Virgen, sometimes called the Mu-kuu-tu-weap, 

 sometimes Little Zion Kiver. It flows due south. East of this is the 

 eastern fork, called thePa-ru-nu-weap. Both branches have their sources 

 at the base of the Piuk Cliffs (Eocene), and at length unite to form the 



