GENERAL DESCRIPIION OF THE COUNTRY. 43 



The igneous protrusions which occur are composed of greenstone or basalt, and are traced from 

 the San Saba mountain, by the head of the Leona, to Santa Rosa, in Mexico, where it unites Avith 

 the main ridge, at an angle of about forty-five degrees. The point where they unite is rich in 

 silver mines. At Santa Rosa the Spaniards had sunk extensive shafts and made a tunnel a 

 mile and a half in length, which was not completed when the revolution of 1825 broke out; 

 since then all extensive operations have heen suspended, and the country, rich in minerals 

 and in the production of the cereals and of tropical plants, has been a prey to the incursions 

 of banditti and Indians, and at this time Wild Cat and his band of Florida Indians are settled 

 near there, to add to the disorder and misrule of this heautiful region. 



It has been observed that these metalliferous rocks generally occur at the junction of two 

 systems, or where some unusual disturbance or change in the geological structure takes place. 

 Hence we may expect to find these silver-bearing rocks along the boundary line, where the 

 upheaving force, after subsiding near the bed of the Gila river, begins again to re-appear to 



tlie soutli. 



The remaining mountain feature of North America, the Appalachian, is referred to here, only 



to illustrate hy comparison the mountain system of the western part of the continent. That 



chain, grand as it is, sinks into insignificance when compared to those I have attempted to 



describe. It is nearly at right-angles to the western chain of mountains, is less elevated, and 



sheds its waters, as is well known, clear on both sides ; on the one side into the Atlantic, and 



Mississipp 



On both sides, the slopes are 



comparatively gentle, and the soil fertile, and, refreshed by frequent showers, yields in abun- 

 dance all that contributes to the wants of man ; on the western side of this slope, between 

 it and the desert border of the Rocky mountains, such an expanse of fertile country exists as 

 can be found, in one body, nowhere else on the face of the globe, producing all the fruits of the 

 earth, including those found in every zone, from the boreal regions to the tropics. Persons 

 faifliliar with its character, as most who read this memoir are, will scarcely be able to compre- 

 hend, still less to believe, the character given to the moxe western and less favored regions 



described in this report. 



In the fanciful and exaggerated description given by many of the character of the western 

 half of the continent, some have no doubt been influenced by a desire to favor particular routes 

 of travel for the emigrants to follow; others by a desire to commend themselves to the political 

 favor of those intererted in the settlement and sale of the lands ; but much the greater portion 

 by estimating the soil alone, which is generally good, without giving due weight to the infre- 

 quency of rains, or the absence of the necessary humidity in the atmosphere to produce a 

 profitable vegetation. But be the motive what it may, the influence has been equally unfortu- 

 nate by directing legislation and the military occupation of the country, as if it were susceptible 

 of continuous settlement, from the peaks of the Alleghanies to the shores of the Pacific. 

 • Between the two most distinctly-marked ranges of mountains, before described, (the Rocky 

 mountains and the Sierra Nevada,) a succession of minor i -p^.-u.^v a 



mountains 



level of the plateau. 



ism ; others present 



their lines of maximum elevation, forming very considerable angles with the general direction, 

 and all, when traced upon a map, exhibit lines varying from right lines to every degree ol 



curvature. 



