CHAPTER XVI. 



THE LOESS. 



The deposit called loess received its name in Germany, 

 where it was first described. But its most remarkable devel- 

 opments are in China and in America. The formation is 

 one of great interest in every respect. It furnishes the most 

 fruitful soil in the world, and is extensively used for the ex- 

 cavation of houses in China and in some parts of America. 

 At the same time it presents the scientific observer with a 

 most attractive but puzzling problem. Professor Pumpelly, 

 who has seen it in all parts of the world, gives the following 

 lucid description of the deposit : 



This remarkable formation covers several hundred thousand 

 square miles in northern China, and larger areas in the rest of 

 Asia. It forms the soil also over an immense area in the west- 

 ern United States. Its thickness varies in China up to two 

 thousand feet, and to one hundred and fifty and two hundred 

 feet in Europe and America. 



Loess is a calcareous loam. It is easily crushed in the hand 

 to an almost impalpable powder, and yet its consistency is such 

 that it will support itself for many years in vertical cliffs two 

 hundred feet high. A close examination shows that it is filled 

 with tubular pores branching downward like rootlets, and that 

 these tubes are lined with carbonate of lime. It is to these 

 that it owes its consistency and its vertical internal structure. 

 It is wholly unstratified, and often where erosion has cut into 

 it, whether one foot or one hundred yards, the walls are ab- 

 solutely vertical. Its vertical internal structure causes it to 

 break off in any vertical plane, but in no other. Hence, when 

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