THE SMITHSONIAN INSTITUTION. 277 



has its origin, near the now deserted Fort Webster, obtains its appella- 

 tion from the creek — a fact which shows its subordinate character. 



4. After having approximately defined the southern extremity of the 

 Rocky Mountains, I have now to follow the course of those detached 

 groups and ridges which, in a certain sense, to be explained hereafter, 

 may be called its southern equivalent. I have already stated that, if 

 such an equivalent exists, it is to be looked lor on the eastern aud not on 

 the western side of the Rio Grande. The traveller coming from San 

 Antonio de Bejar, on his way to El Paso or to the Presidio del Norte, 

 has to pass these mountains, which, situated west of the Pecos river, 

 mark a step from a lower to a higher section of the plateau of western 

 Texas. In steep and singular forms, of a character entirely different 

 from the hills formed by dechvities and detached portions of tableland, 

 as common in western Texas as they are on the head waters of the Pecos 

 and the Canadian, these groups and ridges of plutonic and metamorphic 

 masses, formed by a combination of upheavals and eruptions, emerge 

 from the high surrounding plains. 



On the road to the Presidio del Norte they are passed in the Puerto 

 del Paisano, on the road to El Paso, in the Puerto de las Limpias, or 

 "Wild Rose" Pass, two locahties of the most striking character of wild 

 and romantic mountain scenery — particularly the latter of the two, 

 where the walls of immense porphyritic eruptions are separated into 

 innumerable strange shapes of needles, spires, columns, and spheroids. 

 South of the Presidio del Norte, in the neighborhood of San Carlos, this 

 line of mountains strikes again the Rio Grande, passing from the east- 

 ern to the western side of the river without changing its general direc- 

 tion, the river forming here a great eastern bend, in a long, deep, nar- 

 row, and impassable gorge, through which, in a series of rapids, it pours 

 down from the elevated countr}^ of its upper and middle course into the 

 deep country of the Mexican gulf. Oa its western side, then, the line 

 of mountains bordering the Bolson de Mopimi to the east runs further 

 south through the States of Coahuila, Nuevo Leon, San Luis Potosi, 

 . and Vera Cruz, where it forms the eastern margin of the plateau of 

 Anahuac. 



5. I come now to speak of the Sierra Madre. This denomination 

 has been the cause of many geographical misunderstandings and mis- 

 constructions. It has been understood as a real proper name, while it 

 is but an appellative, meaning the mother chain of mountains — i. e., the 

 principal chain of a country in general, just as the Mexicans call aceqida 

 madre the principal channel of a system of irrigation. Thus the name 

 may occur in different localities without thereby authorizing geogra- 

 phers to conclude that all the mountain chains which have received that 

 denomination belong to one and the same system. It ma}', therefore, 

 really be as some maps have it — I do not know from what source — that 

 a certain chain ms^ofDurango, belonging to the line of ridges which passes 

 over from Texas to Mexico, is known under the name of Sierra Madre, 

 too. But it is certain, and every one who has travelled across Mexico 

 in that latitude knows it, that the Sierra Madre, in the sense generally 

 adopted in the country, is 7iot east but is ivest of Durango, and is passed 

 by the road firom that city to Mazatlan. Of a mountain chain in New 

 Mexico called Sierra Madre, and pretended to be situated on the west- 



