204 DESCRIPTION OF THE PLATES. 



Figure 5. Alluvium of San Pedro ; b. Unconformable gypseous strata of cretaceous period ; 



c. The conglomerates marked b in section 4 ; d. Tracliyte and red felspar rock ; 



e /. Metamorphic quartz and sandstones ; g. Outline of Sierra Calitro, with exposed 



edges of yellow sandstone, a layer of limestone on the summit, with a capping of 



trachytic lava. 

 Figure 6. Gypseous layers ; a. White marl, soft and friable ; b. Greenish aluminous shale ; 



c. Brownish clay, with crystals of gypsum ; dip 4° east. These beds have all been 



denuded. 



PLATE XII. 



Profiles across the district of basin troughs. 

 Figure 1. C. Devonian sandstone of Calitro mountains; S. Upper beds of same; D. Desert 



conglomerate of San Pedro river; L. Carboniferous limestone; >S'e. Serpentine, auriferous; 



T. Trap and augitic dykes. 

 Figure 2. A P. Trachytic rock ; E P. Felspar porphyry ; F. Felspathic dykes ; La. 



Basalt and trappean lavas ; L. Carboniferous limestone ; S S. Permian sandstones. 

 Figure 3. R S. Red sandstone, (Permian ;) S. Whitish grit, (Permian.) The other letters 



are similar to those in sections 1 and 2. In the three profiles, fig. 1, Quaternary 



alluvium ; fig. 5, clay beds ; Nos. 2, 3, 4, connect the beds of different sections together. 



PLATE XIII. 



Profile from Burro mountains to Cook's spring. 

 Figure 1. A. Amygdaloid and trachyte; C. Sandstone conglomerate, with agatized pebbles; 



F. Felspar rock ; m. Talcose strata ; Q. Opaque quartz, with chalcedonic layers ; 



S. Coarse, yellow, metamorphic sandstone. 

 Figure 2. E P. Trachyte and por^Ayry buttes on the Mimbres ; fig 1. Quaternary alluvium; 



E S and S. Eed and white Permian sandstones. 

 Figure 3. Q. Compact quartz, metamorphic sandstone ; R S and W. Eed and white 



sandstones, Permian ; G. Trachytic stratified layer, a white clay rock. 

 Figure 4. T. Greenstone and trap dykes; P p. Trachytic felspar, and chalcedonic rock. 



Other letters correspond with those in foregoing sections. 



Figure 5. Plan of ancient beds of Colorado and Gila rivers at their junction, half a mile 



west of the present junction. 



PLATE XIV. 



Profiles from Cook's spring to the Organ mountains. 



Figure 1. B B B. Dykes and overflows of basalt ; c c c c. Contorted and dislocated Permian 

 grits and sandstones ; s s s. Do. unfractured ; P. Felspar porphyry and trachyte ; 

 D. Quaternary alluvium of Rio Grande valley. 



Figure 2. D. Quaternary alluvium and detritus ; 4. Carboniferous limestone ; S S. Overly- 

 ing sandstones and grits, Permian ; 0. Axis of Organ mountains — granitic porphyry 

 and leptinite ; t. Trap dyke ; x. Veins of argentiferous galena ; Q. Greenish gray 

 sand, with silicified wood, cretaceous. This bed is made to appear too vertical in the 

 drawing. 



Figure 3. L. Carboniferous limestone, underlying the river at the rapids near El Paso, and 

 forming the hills on each bank ; D. Alluvium ; P. Primary granitoid rock. 



Figure 4. B S. Thin band of black shale, 60 feet ; W S R S. Red and white overlying sand- 

 stones ; L. Carboniferous limestone ; d. Alluvium ; A. Synclinal axis of valley of 

 elevation . 



