Rivers.—Of the rivers of the Atlantic versant, the most important are the South Platte, the Arkansas, and the Rio Grande del Norte; those of the Pacific are all members of the great Colorado River. The South Platte has its head waters in Buckskin Mountain, and its earlier tributaries flow from the slopes of the northern part of the Front Range. At its source at Montgomery it has a height above the sea of 11,176 feet; at its exit from the upper cañon it is still 7623, but by the time it reaches Denver it is only 5176. The Arkansas rises in the same district, at a height of 10,176 above the sea, in Tennessee Pass, but as it leaves Chalk Creek has come down to 7877. In the upper part of its course it passes through a cañon from 1000 to 1500 feet in depth. The Rio Grande del Norte has its head waters in the Sawatch range and the Sangre de Cristo range, and flows south through the valley San Luis Park. The river which gives its name to the State belongs to the territory only by some of its most important tributaries, of which it is sufficient to mention the Bear River, and the Gunnison and Grand River, which unite before they pass into the territory of Utah. The numerous minor “creeks” which feed the main streams must not be forgotten in forming an idea of the main features of the country.
Minerals.—Colorado is pre-eminently a mineral district, and to this fact it owes its colonization. It possesses extensive deposits of gold and silver ore, and between the years 1859 and 1872 it furnished to the United States mint upwards of $20,000,000 worth of the former metal and $1,114,542 of the latter. Iron is pretty widely diffused, and zinc and copper occur in many of the mines. Coal is also found extensively on both sides of the main range of mountains; the area occupied by the Tertiary deposits being no less than 7200 square miles, and the annual yield about 200,000 tons. The mining districts are five in number, and are distinguished as the district of the northern mines, the mines of the eastern base, the Conejos county mines, the southern mines, and the mines of Summit County. At Murphy's mine, about twelve miles from Denver, the stratum is about 16 feet thick, and the percentage of fixed carbon is found to be 55·31.
The climate of Colorado is remarkable for its regularity and salubrity. During the day the thermometer not unfrequently rises to 90° in summer, but the nights are always cool and dewless. In winter the weather is generally mild,—the lowest thermometric marking being only 7° below zero, in Middle Park 15°, and in Denver 13°. Snow often lies deep in the higher inhabited districts, but in the lowlands it is never more than 10 or 12 inches, and it disappears again almost immediately. All through the year the atmosphere is so dry and light that butcher meat can be preserved by the simplest process of desiccation. Between July and October there is very little rain, day after day bringing a bright and cloudless sky. “An air more delicious to breathe,” says Bayard Taylor, “cannot anywhere be found; it is neither too sedative nor too exciting, but has that pure, sweet, flexible quality which seems to support all one's happiest and healthiest moods.” For asthmatic and consumptive patients it exercises a restorative influence which cannot be disputed; and the State consequently promises to become an extensive sanatorium for the eastern districts of the continent. The only flaw in the climate of Colorado is its violent storms of wind, and in some parts of the country heavy falls of hail. It would seem, however, that the humidity is on the increase; and whatever be its cause, the change is quite perceptible since the colonization of the territory. The Cache à la Poudre, for instance, is said to be yearly increasing in volume, and streams which formerly dried up in the summer now maintain a continuous flow. Among the secondary hygienic advantages of which Colorado can boast, the mineral wells hold an important place. They occur in various parts of the country, and belong to different classes. Chalybeate waters are found at Manitou, Carlisle, and Red Creek; soda springs at Manitou, Trinidad, and Cañon City; sulphur springs at Fairplay, on the Navajo River, and at Idaho springs; and thermal springs, partly sulphur and partly soda, exist at Pagosa, in the Middle Park, in Seguache County, at Wagon Wheel Gap, and at Del Norte. Manitou is already becoming a fashionable watering-place; the fountains and the surrounding land were purchased by a company in 1870; and in 1873 there were already six large hotels and numerous private residences erected round the spot. In the lowland districts water for drinking is very scarce; but supplies can frequently be obtained by the sinking of Artesian wells.
