235 



manner during the summers of 1888, 1889, 1890. The 

 results of his work are contained in the Report on the 

 Kamloops Map Sheet [4]. 



Physiography. 



As viewed from the wide, open valley of Thompson 

 river, the Kamloops district presents a hilly and even 

 mountainous relief, the bordering summits rising from 

 4,000 to 5,000 feet (1,200 to 1,500 m.) above the level of 

 the river. A broad summit view, however, explains why 

 it is included among the Interior Plateaus of British 

 Columbia, for from about the 4,000-foot (1,200 m.) level, 

 there stretches as far as the eye can see a series of gently 

 undulating and plateau-like upland surfaces. Within 

 the upland, the younger valleys appear to be deeply 

 entrenched. 



Both the annual and daily range of temperature is great. 

 On account of the very slight rainfall, the region is common- 

 ly known as the "Dry Belt of British Columbia." 



Where irrigated, the semi-arid land of the valleys, 

 commonly covered with sage brush, cactus, scattered 

 yellow pine, and thickets of poplar, is very productive 

 of fruits and vegetables. The grassy "park country" of 

 the upland affords good grazing for cattle, and a supply 

 of timber for the ranches. 



For the explanation of relief in the district at least 

 three cycles of erosion must be considered: one in Cre- 

 taceous; one in pre- Miocene; and the latest in Pliocene 

 time. It is to the Pliocene erosion cycle that the present 

 upland topography chiefly owes its development. 



The facts upon which the above tentative conclusions 

 are based are as follows: — 



1 . Early Tertiary (Eocene ?) conglomerates rest directly 

 upon the upper Jurassic batholith south of Walhachin. 

 The conglomerate is largely composed of well water-worn 

 boulders of granite and Paleozoic metamorphics. As 

 granite batholiths consolidate under considerable thick- 

 nesses of superincumbent material, such conditions would 

 necessitate the removal by erosion of the entire cover 

 from the batholith. A great thickness of rock must, 

 then, have been removed during the Cretaceous period. 



2. The absence of Upper Cretaceous rocks in the dis- 

 trict, and the entire absence of Cretaceous rocks east of 



