10 CONTENTS. 



CHAPTER XXII. 



Volcanic or disturbed district. 



Burro mountains. — Igneous and metamorphic rocks of Penasquitas. — Kegion about Ojo dela V ea. — Eed sandstone. — Character 

 of spring. — ^Trachyte buttes. — Enumeration of the stratified roclis near the Mimbrcs. — Structure of the Mimbres valley. — 

 Agua Caliente. — Vicinity of the spring. — Properties and temperature of the water. — Carbonic acid gas. — Volcanic disturb- 

 ance of the region. — Giants of tha Mimbres — Plain east of the Mimbres river. — Picacho. — Elevation and structure — 

 Trachyte and greenstone dykes. — Observations on the Picacl'.o. — Structure of the vicinity of Cook's spring. — Character 

 of the water. — Jornada. — Basalt district. — Extent. — Ti'achyte out-pouring. — Monument Hill. — Mesas of Kio Grande val- 

 ley. — Sandstone detritus. — Picacho of Mesilla. — Topography of vicinity. — Mesilla valley, extent. — River bottom, fertility. 



CHAPTER XXIII. 



0/ the mountain systems. 

 Eemarks upon. — Pinaleno mountains, parallel ranges. — Geographical extent. — Classification of the stiata. — Igneous 

 rocks . — Ape of the range. — Mogollon mountains. — Interval between it and the former range. — Geology of. — Igneous 

 axis, importance of. — Of the lesser r.anges and isolated hills between the San Pedro river and the Colorado desert. — Organ 

 mountains, extent, direction, axis. — Stratified rocks of. — Carboniferous limestone. — Minerals of. — East side of the 

 range. — Jornada del Muerto. — Relative ages of the igneous rocks of the system. — Of the sandstones west of the Organ 

 mountains. 



CHAPTER XXIV. 



Of the present supply of ivater, and of the feasibility of obtaining abundant supplies by Artesian 



borings. 



Only a portion of the route deficient in the supply of water. — Extent of this district. — Geological summary. — Meteorology. — 

 Region of summer rains. — Elevation of the district. — Annual fall of rain — Causes of the diminution of rain westward. — 

 Quantity absorbed by the soil. — Contrast of a north temperate and an inter- tropical zone. — Substitutes for Artesian welis. — 

 Water tanks — Ordinary wells. — General conclusions. — Localities of natural supply on route. — Cook's spring. — Rio Mim- 

 bres. — Ojo de la Vaca. — Valle del Sauz. — Playa de losPimas. 



CHAPTER XXV. 



Economical geology. 



Localities of supply of building stone, and nature of material. 



CHAPTER XXVI. 



Tabular vieto of the geological structure of southern New Mexico, near the Gila. 



CHAPTER XXVII. 



Chemical analyses. 



Kative copper ore. — San Pedro marl. — Carboniferous limestone. — Argentiferous galena. — Trachytes. — Soil from mesa ot 

 Sonora desert. — Soil from Pimas plains. — Soil near mouth of the Gila river. — Remarks upon the soils. 



CHAPTER XXVIII. 



List of minerals collected. 



CHAPTER XXIX. 



Report upon the palcconlology of the survey, by T. A. Conrad. 



CHAPTER XXX. 



Order of position of Californian strata. 



