VALLEYS IN LOW LATITUDES 119 



section. It partakes more nearly of the features of a U-shaped 

 glacial valley than of the typical V-shaped valley familiar to geologists 

 as the product of running water at high gradients; but obviously 

 glacial action has had nothing to do with the sculpturing of this 

 valley. It may be exceptional in this feature, which is possibly 

 dependent on differences in the character of the lava that makes up 

 this part of the island. Unfortunately we were unable to visit any 

 of the other valleys of the island. The lack of talus at the foot of 

 the usually steep slopes was notable and in full consonance with the 

 similar absence in the valleys on the eastern border of the Mexican 

 plateau. 



On a railway journey from Yokohama to Kyoto, Japan, in lati- 

 tude about 35° N., the relation of the broad flats of the lowlands 

 to the higher slopes of the uplands attracted especial attention. As 

 in the preceding cases, their junctions were decidedly more abrupt 

 than is usual in like cases in our northern latitudes in America. The 

 first impression received, due no doubt to inherited geologic habit, 

 favored the assignment of the flats to sea work and the abrupt 

 angle they made with the uplands to the girdling of the sea margin. 

 This view, on closer study, seemed probably erroneous. The plains 

 appeared to be aggradation bottoms, in the main, built up or at 

 least sheeted over by the numerous rivers that emerge from the 

 mountains. The streams across them have notable gradients. The 

 abruptness is thus probably in part constructive, rather than erosional, 

 but is probably also in part erosive and perhaps of the Mexican type. 



In South China features of an analogous order were noted. The 

 Si Kiang, or West River, has a long course through the moderately 

 mountainous country which is characteristic of Southern China. 

 From the bottoms that adjoin the river, the hill slopes usually rise 

 promptly and steeply. The mountain range west of Sam Shui in the 

 province of Kwang Tung was estimated to reach 1,000-1,200 feet 

 and perhaps at points 1,500 feet in elevation. Very little talus was 

 seen on its slopes or on any of the mountain slopes. The soil is thin, 

 and under the climatic conditions prevailing here the hills have a 

 limited vegetal covering and are very scantily cultivated. There 

 are, however, lower hills that are often well rounded, with clean, 

 smooth slopes. 



