Chap. XIII. YALLEY OF THE DEVIL'S EIVER. 419 
It is asserted that this process may be watched through- 
out West Texas ; that the increasing growth of trees and 
shrubs changes the climate and increases the amount of 
rain, so that by degrees the steppes will be covered with 
woods and thickets. 
Whether every fact in this chain of sequences is correct 
I cannot say ; but the belief in a change of climate and an 
increased amount of rain was at that time very general in 
West Texas. The old Mexican inhabitants ascribed the 
increased humidity to some mysterious influence of the 
North Americans, the change having apparently come with 
them. The subsequent droughts, however, from which 
Texas suffered so severely, must have shaken this belief. 
The sudden appearance of a young mezquite vegetation 
after so long a period of obstruction to its growth, may be 
explained by its growth from the roots, since the algarobbia 
sends out very long and deep roots. 
We continued our journey four days, partly through the 
valley of the Devil's River, partly through lateral branches 
of the same, and over adjoining table-land. This locality is 
one of the most interesting 1 have seen in America. The 
valley, with its branches, is literally a defile through the 
plateau, and opens into that of the Rio Grande, where this 
enters the lowland of Texas. At the upper part of the 
valley our caravan passed over masses of heaped-up blocks 
and stones, which, in places, covered the ground from one 
mountain's side to the other. These heaps are terrible 
indications of the fearful power exercised by the periodical 
floods. I saw drift wood remaining high up the trees 
between forked branches, showing to what an incredible 
height the valley was sometimes filled with water. These 
floods are however of very short duration. Where we first 
entered the valley it was quite dry; but farther on, the 
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