708 The Chinese Loess Puzzle. [December, 
gin with the tendency which this material possesses — as already 
noticed — to divide into masses separated by vertical planes; a 
peculiarity which is not properly cleavage, neither is it exactly 
what geologists call jointing, but something near akin to it.. As 
a result of this tendency, we find that the rivers which run 
through the loess-covered districts are bordered by absolutely 
vertical walls of this material, sometimes hundreds of feet in 
height. Given the elements of great thickness of the deposits, 
extreme facility of erosion due to the softness of the mass, and 
the tendency to vertical cleavage, and it can easily be imagined 
that the resulting forms left from the action of erosive agencies 
must be extremely complex and peculiar. Indeed, as described 
by Richthofen, the loess-covered region is certainly one of the 
most curious portions of the earth’s surface. It somewhat resem- 
bles the Colorado plateau, in being deeply and intricately fur- 
rowed by drainage channels of great depth, and proportionately 
very narrow. In the Colorado region, however, the walls of the 
cafions, as these gorges are there called, are never vertical, though 
usually quite steep, and the material on which the water exer- 
cises its erosive power has a greater variety of texture and color 
than that offered by the loess, which is remarkably homogeneous 
from top to bottom. The difficulty of traversing such a region, 
or even of engineering roads through it, can readily be imagined. 
It is not so much of a task to keep on one main divide between 
two systems of gorges; but to go across the country in any fixed 
direction is almost an impossibility. Tunnels and spiral stair- 
ways in the mass of the loess must often be resorted to. dn 
short, the configuration of the surface is, as Richthofen remarks, 
most fantastic and curious. “ Wide chasms are surrounded by 
castles, towers, peaks, and needles, all made up of yellow earth, 
between which gorges and chasms radiate labyrinthically upwards 
into the walls of solid ground around. High up on a rock of 
earth, steeper than any rock of stone, stands the temple of the 
village, or a small fortress which affords the villagers a safe re- 
treat in times of danger. The only access to such a place is by 
a spiral stairway dug out within the mass of the bluff itself. In 
this yellow defile there are innumerable nooks and recesses, often 
enlivened by thousands of people, who dwell in caves dug out m 
the loess!” : ; 
Millions of human beings live in habitations excavated in this 
1 Richthofen, Letter on the Provinces of Chili, Shansi, Shensi, and S2’-chwan. 
Shanghai, 1872. : : 
