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XI. 
THE RIO DEL FUERTE OF WESTERN MEXICO, AND ITS 
TRIBUTARIES. By KINSLEY DRYDEN DOYLE, M.A., 
Assoc. M. Inst. C.H. (Pxates VI.-XV.) 
[COMMUNICATED BY PROFESSOR J. JOLY, F.R.S.| 
[Read Arrit 19; Received for Publication May 30; Published Avcusr 31, 1899.] 
‘Tue Fuerte river is a powerful stream, named from its torrential 
character, draining a basin of 17,000 square miles, including that 
part of Western Mexico called the Sierra Tarahumare, and falling 
into the Californian Gulf just south of the 26th parallel of north 
latitude. (See map, Pl. XV.) The rainfall of this region is a 
mean between the extreme aridity of the Colorado desert and the 
tropical copiousness of Tepic and Jalisco; there is a long dry 
season from November to June, broken only by a few thunder- 
showers, during which the vegetation is mostly leafless; and the 
only green objects in the low country are numerous varieties of 
cactus, agaves, and a few other kinds of plants whose bark serves 
the purposes of leaves, except in places where the roots can reach 
water. The prolonged drought dries up all the rivulets in the 
low land or “tierra caliente” as it is called locally, but the 
immense rock masses of the plateau—rightly named Sierra Madre, 
mother of mountains—store up and give out a perennial stream, 
never falling below 64,000 cubic feet per minute. 
The Fuerte is 275 miles long from source to mouth, and the 
united river for a third of the whole length flows through the low 
plain ; the remaining part and all the chief tributaries pass through 
rugged foot hills and in deep canons worn in the Sierra itself. 
This country was traversed by the author in 1897 from west 
to east, but it will be more convenient for the purpose of description 
to start near the watershed. 
Proceeding therefore from the town of Chihuahua on the 
Mexican Central Railway, one traverses the central plain, gra- 
dually rising from east to west towards the wave crest of the great 
slope ; for the first 70 miles the road or track goes over a rugged 
