GEOLOGICAL RESEARCH IN EASTERN ASIA. 287 



Streams doing the greater part of the work ; that during an epoch 

 shortly preceding the present, topographic conditions were unhke 

 those now existing, and were favorable to the accumulation of 

 alluvium in places where its situation is now peculiar, and we reason 

 that the same agencies, streams and winds interacting, spread the 

 deposit initiallj'. 



ON THE INFLUENCE OF MAN. 



Denudation and Terracing. — Northern China is remarkably bare of 

 trees, shrubs, or herbage, except shade-trees, fruit-trees, crops, and 

 on steep hillsides strong-rooted, ineradicable grass. This condition 

 is the work of man. Unchecked by public opinion or by regard 

 for future generations, the Chinese have destroyed vegetation in 

 supplying individual need. The process still continues, as, pressed 

 by the necessity for fuel, they scratch up the scanty grass by the 

 roots with a specialh' contrived tool. 



The effects of denudation are more pronounced in Shantung than 

 in any other province visited. For 3,000 years or more the process 

 has been efl&ciently promoted by a dense population, which has 

 removed not only vegetation, but also soil, wherever the latter was 

 not deep enough to grow crops or did not present a nearly level 

 surface. The disastrous effects of heavy rains must early have led 

 to the practice of terracing, which is now universal and which is 

 extended to the utmost limits of gathering soil. In a few rare in- 

 stances in Shantung we found thin soil on steep slopes near moun- 

 tain tops, dug up above a stone wall with the obvious purpose that 

 it should be washed down and caught. Everywhere below was the 

 perfected system of terraces — soil reservoirs. 



Northern Shausi presents similar conditions, but in a less advanced 

 stage. The Wutai-shan affords an especially interesting example. 

 The mountains were forest-covered with pines up to the time of the 

 Emperor Chien Lung, who, about 160 years ago, issued an edict 

 that the district which had previously been inhabited only by priests 

 should be populated. The trees were rapidly destroyed ; the great 

 bare mountains are now at the mercy of the elements, and huge 

 gullies, eating their way toward the summits, tell what progress 

 denudation is making, as do also the wastes of gravel and sand along 

 the streams. The method of terracing, in general use elsewhere, is 

 but rudely developed in the Wutai, yet a beginning is made, and 

 the necessities of agriculture will demand that it be perfected. 



In southern Shensi the climate is less rigorous and vegetation is 

 more luxuriant. There forests of pine still cover large areas in dis- 

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