10 
CONTENTS. 
CHAPTER XXII. 
Volcanic or disturbed district. 
Burro mountains.—Igneous and metamorphic rocks of Penasquitas.—Region about Ojo dela V ca.—Red sandstone.—Character 
of spring.—Trachyte buttes.—Enumeration of the stratified rocks near the Mimhrcs.—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 the Mimbres.—Plain east of the Mimbres river.—Picacho.—Elevation and structure — 
Trachyte and greenstone dykes.—Observations on the Picacho.—Structure of the vicinity of Cook’s spring.—Character 
of the water.—Jornada.—Basalt district.—Extent.—Trachyte out-pouring.—Monument Hill.—Mesas of Rio Grande val¬ 
ley.—Sandstone detritus.—Picacho of Mesilla.—Topography of vicinity.—Mesilla valley, extent.—River bottom, fertility. 
CHAPTER XXIII. 
Of the mountain systems. 
Remarks upon.—Pinaleno mountains, parallel ranges.—Geographical extent.—Classification of the strata.—Igneous 
rocks.—Age of the range.—Mogollon mountains.—Interval between it and the former range.—Geology of.—Igneous 
axis, importance of.—Of the lesser ranges 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 XXIY. 
Of the present supply of water, 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 wells._ 
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 view of the geological structure of southern New Mexico, near the Gila. 
CHAPTER XXVII. 
Chemical analyses. 
Native 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 palaeontology of the survey, by T. A. Conrad. 
CHAPTER XXX. 
Order of position of Californian strata. 
