245 



Kilometres train at many places, represents an old river 

 channel. 



A broad belt of Coldwater conglomerate, 

 sandstone, and shale outcrops about one mile 

 (i-6km.) south of the railroad. These sedi- 

 ments represent an old Eocene river course, 

 later uplifted, eroded and protected from further 

 erosion by remnants of younger lava flows. 



The train after leaving the Walhachin terraces, 

 winds around points of Triassic rocks and 

 through alluvial fans built up by tributary 

 creeks, until it reaches the 37th mile-post, 

 where a granitic boss is encountered. The 

 granodiorite extends across the river east of 

 Eight Mile creek, and, a couple of miles north, 

 disappears under the lava cap of the Kamloops 

 volcanic group. 

 38-4 m. Semlin — Semlin is a railroad siding named 

 61-7 km. from the broad, hanging Semlin valley which 

 joins the main Thompson valley at this point. 

 The Semlin valley is probably an old course of 

 Bonaparte creek. 



A short distance west of Semlin station, the 

 railroad cuts through the basal portion of a 

 syncline in the Kamloops volcanics. The 

 syncline, which is a continuation of the Savona 

 mountain remnant, extends northward across 

 the river where it widens out into a broad 

 synclinal belt capping the hill tops. The se- 

 quence of the rocks as exposed in the rock cuts, 

 shows lavas of trachytic habit, succeeded 

 above by basaltic lava with columnar jointing. 

 The basalt passes into a dense bluish-black 

 phase with pronounced ball-and-socket jointing. 

 The lava passes upward into grayish tuffs and 

 coarse agglomerates containing fragments of 

 basalt. The upland in this vicinity is a pene- 

 plain which truncates the slightly tilted Kam- 

 loops volcanics. One mile (i-6 km.) west of 

 Semlin, the railroad emerges from the lava 

 syncline and cuts through great thicknesses of 

 alluvial silts, gravels and till. The clay silt is 

 quite consolidated and stands in vertical cliffs 

 forming in many places weird "hoodoos". 



