LOESS WEST OF FIRST AND SECOND RANGES 131 



turns off to the south, to meander along the low plain intervening be- 

 tween it and the mountains in that direction, at a level 200 feet lower 

 than its former bed. 



Loess west of the first Mountain Range 



On crossing the first low range of mountains, which in this vicinity are 

 nowhere more than 3,000 feet in height, but rise south of the Hunho to 

 a height of 6,000 or 7,000 feet, we come into a valley from 15 to 20 miles 

 in width and extending 60 or 70 miles in an east-and-west direction, 

 through which tributaries of the Hunho reach the main river on either 

 side from opposite directions. At an elevation of 40 or 50 feet above the 

 flood-plain of the northern tributary numerous fresh-water shells are 

 found, indicating an expansion of still water over a considerable area. 

 For a distance of 30 miles from Huilasen to Chiming the road follows 

 near the base of the mountains which border the west side of this plain. 

 No streams of any great length come down from that direction, but all of 

 them, short as they are, are marked in front of their mouths by extensive 

 fans or cones of dejection, there being much coarse material in the direct 

 axes of these cones, or deltas as they might be called, shading off into 

 deep deposits of loess on either side, so that the road leads regularly 

 across deep deposits of loess which often stand in walls with perpendic- 

 ular faces from 20 to 30 feet in height along the road, alternating with 

 lines of coarse gravel and river pebbles standing at somewhat higher 

 level. Here, again, it would seem difficult to explain the extension of 

 these delta-like deposits into the plain, except on the theory that the 

 material was originally brought by the streams into a body of standing 

 water, which determined the order of the deposition. Certainly, at the 

 present time the loess is undergoing rapid erosion and is everywhere 

 being rapidly swept down to lower levels. 



Loess west of the second Mountain Range 



From Chiming the road leads up the Hunho river through a remark- 

 able gorge which penetrates the second range of mountains, leading after 

 a few miles into another broad valley which stretches out its arms in a 

 northeast and southwest direction between the low mountain chain and 

 the parallel border of the Mongolian plateau. This is imperfectly drained 

 by the upper tributaries of the Yangho, one of the main branches of the 

 Hunho. This is not, however, a continuous plain, since the surface is 

 often broken by rocky protuberances of considerable extent. There is, 

 however, a pretty well marked border of the plateau all along the western 



