CHAPTER XI, 
PHYSIOGRAPHY OF NORTHWESTERN CHINA. 
By BAILEY WILLIS. 
INTRODUCTION. 
The physiography of the plains and mountains through which we 
passed can not well be discussed according to limited districts, as can the 
geological formations. We have to deal with the features of the surface, 
which are, it is true, local, but which are so intimately related to those 
of adjacent and even of remote districts, that they should be treated as 
a whole. In the following account I shall consider the aspect of the different 
regions through which we traveled, from Pau-ting-fu, Chi-li, to Si-an-fu, 
Shen-si, first describing them as we saw them along our route, and subse- 
quently grouping them according to relative age in order to discuss their 
significance in terms of mountain growth. 
DESCRIPTION OF FEATURES ALONG THE ROUTE. 
The plain (Pau-ting-fu to Si-ta-yang).—Pau-ting-fu lies in the alluvial 
plain of northern China, at an altitude of 60 feet, 18 meters, above sea, about 
25 miles, 40 kilometers, from the foothills of the mountains of northwestern 
Chi-li. Our route extended thence through Wan-hién, T’ang-hién, and 
Si-ta-yang.* The great plain presents a monotonous surface, with no 
natural features which approach in prominence those of artificial origin. 
At Wang-tou-hién there is an artificial hill, probably 12 meters high, upon 
which a temple is built, which is conspicuous from all points of view on 
the adjacent plain. ‘The streams are but slightly incised and the surface 
frequently slopes away from their banks, which are confined by more or 
less massive dikes. The rise of the plain toward the foothills is exceedingly 
gradual. In a distance of 12 miles, 19 kilometers, from Pau-ting-fu to 
Pei-p’u this rise is but 40 feet, 12 meters, and along our route the 100-foot 
contour winds in a general way parallel to the outer line of the foothills, 
at a distance of 4 to 5 miles, 6.5 to 8 kilometers, from them, while the 200- 
foot contour closely defines their bases. We may say that the slope of the 
plain varies, from 3 feet to the mile, .6 meter to the kilometer, at some 
distance from the hills, to 10 feet per mile, 1.8 meters per kilometer, as they 
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* See atlas sheets G I and F I. 
