VI CONTENTS. 



CHAPTER III. 



OEOLOOICAL FEATCKES OF THE KIO GRANDE VALLEY, FROM EL PASO TO THE MOUTH OF THE PECOS HIVKR. 



Page. 



Lower limits of the EI Paso basin . . 49 



Near Presidio del Norte . 50 



Bofecillos - - - - 52 



Comanche trail - - - 54 



Canon of San Carlos 54 



Falls of San Carlos 55 



Chisos mountains 56 



San Carlos valley -- 57 



Vado Flecha - 58 



Cauou of San Vicente _ 58 



Caiion Carmel - 59 



Peak ' ' Picotera " 60 



Lagoon formation in the upland plains 60 



Santa Rosa and route to Eagle Pass , 61 



CHAPTER IV. 



GEOLOGICAL OBSERVATIONS ON THE COUNTRY ALONG THE BOUNDARY LINE LYING BETWEEN THE IIItH DEG..EB OF LONGITUDE AND 



THE RIO COLORADO. 



Geographical situation , 62 



General geological structure. - -- 62 



Diluvial main 63 



Hypsometrical features of the mountain system 64 



Spanish topographical expressions 65 



Sierra del Pajarito 66 



Valley of Los Nogales .. 67 



Sierras Janos and Atascosa 68 



The Arizona mines 69 



Sierra Escon dida 69 



Sierrita del Grauizo _ 70 



Sierra del Pozo Verde 70 



Picacho " Babuqui vari' ' 70 



Sierra de la Union 71 



Cordillera de Cobota 71 



Sierras Arteza and Soiii 71 



Commencement of the Colorado desert 71 



Sierra de los Linderos - 72 



Siena de la Nariz 72 



Sierra de la Laguna 72 



Sierra del Ajo 72 



Cienaja de Sonoy ta ._ 74 



Sierras Guchibabi and Sonoy ta 74 



Quitobaquita 74 



Salada hills - 75 



Mal-pais of Sierra Tule 76 



Sierras TuM and Tinaja Alta 76 



Summary _ 77 



