THE 0^T:RLAND route OGDEISr TO SAN FRANCISCO. 205 



fo 



summer J as a precaution against 

 ^elevation 5.758 feet), Yuba Pass 



(5j614 feet), and Smart (5;351 feet) are unimportant stations in the 



snowsheds. 



stem 



is inierestingj and an account of it may be obtained by conversing 



with 



Smart 



right shows the South Fork of Yuba River in its now rapidly deepening 



vulley far below. The river here turns sharply north 

 Emigrant Gap. ^^^ immediately disappears into a very narrow and 

 Elevation 5,2^ feet. (Jeep rockv gorze. This is a striking example of what 



Omaha 1,610 miles. . -^ '^^^-. , , i 



IS known among physiographers as stream capture. 

 The part of the river abeady passed is the former headward por- 

 tion of Bear River, which now rises near this point and flows 



h a smooth, grassy gap, kno^vTi as Emigi-ant 

 Gap. Another stream on the north, the original South Fork of 



o 



manner 



streams^ cut its canyon faster and deeper than that of the ancient 

 Bear River was cut and finally worked back into the Bear River val- 

 ley and, tapping that stream, drained off its water tlirough the narrow 

 canyon to the north. (See fig. 17, on sheet 23, p. 214.) The present 

 Bear River approaches within a quarter of a mile of the railroad just 

 beyond Gold Run. The evidence of this interesting bit of ancient 



remains in view but moment 



throug 



American River svstem 



EmiOTant Gao is the first station on the descent which 



surroundinsT aOTicultural 



The railroad cuts 



expose slates and micaceous schists (Calaveras formation) which 

 belong to the Carboniferous system. Here may be noted a change 

 from the upper region where glaciers have scoured the rocks clean of 

 all loose material to the lower region where a mantle of soil and disin- 

 tesrated rock 2:ives better opportunity for forest growth. 



imbered hills 



curve 



Am 



Blue Canyon. ^f t]ie characteristic flat-topped, lava-capped ridges 

 Elevation 4,701 feet, ^f the mid-SieiTa slope. (See PI. XLIX, B, p. 207.) 

 Omaha 1,615 miles. ^^ ^^^^ ^^ ^^^ sno^sheds is BcaT at hand. Beyond 



them, as the road winds in and out on the mountain side, distant 

 views bring out with great distinctness the evenness of the sky 

 line that is significant of the smoothness of the older (early Ter- 

 tiary) topographic surface by whose uplift and westward tilting in 

 late Tertiary time the Sierra Nevada came into being as a mountain 



