Note 5 — ON STEPPES AND DESERTS.

p. 2—“Compared with the Llanos and Pampas of South America, or even with the Prairies on the Missouri.”

Our physical and geognostic knowledge of the western mountain region of North America has recently been enriched by the acquisition of many accurate data yielded by the admirable labours of the enterprising traveller Major Long, and his companion Edwin James, but more especially by the comprehensive investigations of Captain Frémont. The knowledge thus established clearly corroborates the accuracy of the different facts which in my work on New Spain I could merely advance as hypothetical conjectures regarding the northern plains and mountains of America. In natural history, as well as in historical research, facts remain isolated until by long-continued investigation they are brought into connection with each other.

The eastern shore of the United States of North America inclines from south-west to north-east, as does the Brazilian coast south of the equator from the Rio de la Plata to Olinda. On both these regions there rise, at a short distance from the coast line, two ranges of mountains more nearly parallel to each other than to the western Andes, (the Cordilleras of Chili and Peru), or to the North Mexican chain of the Rocky Mountains. The South American or Brazilian mountain 30system, forms an isolated group, the highest points of which, Itacolumi and Itambe, do not rise above an elevation of 900 toises, or 5755 English feet. The eastern portion of the ridge most contiguous to the sea is the only part that follows a regular inclination from S.S.W. to N.N.E., increasing in breadth and diminishing in general elevation as it approaches further westward. The chain of the Parecis hills approximates to the rivers Itenes and Guaporé, in the same manner as the mountains of Aguapehi and San Fernando (south of Villabella) approach the lofty Andes of Cochabamba and Santa Cruz de la Sierra.

There is no direct connection between the two mountain systems of the Atlantic and South-sea coasts (the Brazilian and the Peruvian Cordilleras); Western Brazil being separated from Eastern or Upper Peru by the low lands of the province of Chiquitos, which is a longitudinal valley that inclines from north to south, and communicates both with the plains of the Amazon and of the Rio de la Plata. In these regions, as in Poland and Russia, a ridge of land, sometimes imperceptible (termed in Slavonic Uwaly), forms the line of separation between different rivers; as for instance, between the Pilcomayo and Madeira, between the Aguapehi and Guaporé, and between the Paraguay and the Rio Topayos. The ridge (seuil) extends from Chayanta and Pomabamba (19°–20° lat.,) in a south-easterly direction, and after intersecting the depressed tracts of the province of Chiquitos, (which has become almost unknown to geographers since the expulsion of the Jesuits,) forms to the north-east, where some scattered mountains are again to be met with, the divortia aquarum at the sources of the Baures and near Villabella (15°–17° lat.)

This water-line of separation which is so important to the general intercourse and growing civilization of different nations corresponds in the northern hemisphere of South America with a second line of demarcation (2°–3° lat.) which separates the district of the Orinoco from that of the Rio Negro and the Amazon. These elevations or risings in the midst of the plains (terræ tumores, according to Frontinus) may almost be regarded as undeveloped mountain-systems, designed to connect two apparently isolated groups, the Sierra Parime and the Brazilian highlands, to the Andes chain of 31Timana and Cochabamba. These relations, to which very little attention has hitherto been directed, form the basis of my division of South America into three depressions or basins, viz., those of the Orinoco in its lower course, of the Amazon, and of the Rio de la Plata. Of these three basins, the exterior ones, as I have already observed, are Steppes or Prairies; but the central one between the Sierra Parime and the Brazilian chain of mountains must be regarded as a wooded plain or Hylæa.

In endeavouring by a few equally brief touches to give a sketch of the natural features of North America, we must first glance at the chain of the Andes, which, narrow at its origin, soon increases in height and breadth as it follows an inclination from south-east to north-west, passing through Panama, Veragua, Guatimala, and New Spain. This range of mountains, formerly the seat of an ancient civilization, presents a like barrier to the general current of the sea between the tropics, and to a more rapid intercommunication between Europe, Western Africa, and Eastern Asia. From the 17th degree of latitude at the celebrated Isthmus of Tehuantepec, the chain deflects from the shores of the Pacific, and inclining from south to north becomes an inland Cordillera. In Northern Mexico, the Crane Mountains (Sierra de las Grullas) constitute a portion of the Rocky Mountains. On their western declivity rise the Columbia and the Rio Colorado of California; on the eastern side the Rio Roxo of Natchitoches, the Canadian river, the Arkansas, and the shallow river Platte, which latter has recently been converted by some ignorant geographers, into a Rio de la Plata, or a river yielding silver. Between the sources of these rivers rise in the parallels of 37° 20′ and 40° 13′ lat., three huge peaks composed of granite, containing little mica, but a large proportion of hornblende. These have been respectively named Spanish Peak, James or Pike’s Peak, and Big Horn or Long’s Peak.^[K] Their elevation exceeds that of the highest summits of the North Mexican Andes, which indeed nowhere attain the height of the line of perpetual snow from the parallels of 18° and 19° lat., or from the group of Orizaba, (2717 toises, or 17,374 English feet), and of Popocatepetl (2771 toises, or 17,720 English feet) to Santa Fé and Taos in New Mexico. 32James’ Peak (38° 48′ lat.) is said to have an elevation of 11,497 English feet. Of this only 8537 feet have been determined by trigonometrical measurement, the remainder being deduced in the absence of barometrical observations, from uncertain calculations of the declivity or fall of rivers. As it is scarcely ever possible, even at the level of the sea, to conduct a purely trigonometrical measurement, determinations of impracticable heights are always in part barometrical. Measurements of the fall of rivers, of their rapidity and of the length of their course, are so deceptive, that the plain at the foot of the Rocky Mountains, more especially near those summits mentioned in the text, was, before the important expedition of Captain Frémont, estimated sometimes at 8000 and sometimes at 3000 feet above the level of the sea.^[L] From a similar deficiency of barometrical measurements, the true height of the Himalaya remained for a long time uncertain; now, however, science has made such advances in India, that when Captain Gerard had ascended on the Tarhigang, near the Sutledge, north of Shipke, to the height of 19,411 feet, he still had, after having broken three barometers, four equally correct ones remaining.^[M]

Frémont, in the expedition which he made between the years 1842 and 1844, at the command of the United States Government, discovered and measured barometrically the highest peak of the whole chain of the Rocky Mountains to the north-north-west of Spanish, James’, Long’s, and Laramie’s Peaks. This snow-covered summit, which belongs to the group of the Wind River Mountains, bears the name of Frémont’s Peak on the great chart published under the direction of Colonel Abert, chief of the topographical department at Washington. This point is situated in the parallel of 43° 10′ north lat., and 110° 7′ west long., and therefore nearly 5° 30′ north of Spanish Peak. The elevation of Frémont’s Peak, which according to direct measurement is 13,568 feet, must therefore exceed by 2072 feet that given by Long to James’ Peak, which would appear from its position to be identical with Pike’s Peak, as given in the map above referred to. The Wind River Mountains constitute the dividing ridge (divortia aquarum) between the two seas. “From the summit,” 33says Captain Frémont in his official report,^[N] “we saw on the one side numerous lakes and streams, the sources of the Rio Colorado, which carries its waters through the Californian Gulf to the South Sea; on the other, the deep valley of the Wind River, where lie the sources of the Yellowstone River, one of the main branches of the Missouri which unites with the Mississippi at St. Louis. Far to the north-west we could just discover the snowy heads of the Trois Tetons, which give rise to the true sources of the Missouri not far from the primitive stream of the Oregon or Columbia river, which is known under the name of Snake River, or Lewis Fork.”

To the surprise of the adventurous travellers, the summit of Frémont’s Peak was found to be visited by bees. It is probable that these insects, like the butterflies which I found at far higher elevations in the chain of the Andes, and also within the limits of perpetual snow, had been involuntarily drawn thither by ascending currents of air. I have even seen large winged lepidoptera, which had been carried far out to sea by land-winds, drop on the ship deck at a considerable distance from land in the South Sea.

Frémont’s map and geographical researches embrace the immense tract of land extending from the confluence of Kanzas River with the Missouri, to the cataracts of the Columbia and the Missions of Santa Barbara and Pueblo de los Angeles in New California, presenting a space amounting to 28 degrees of longitude (about 1360 miles) between the 34th and 45th parallels of north latitude. Four hundred points have been hypsometrically determined by barometrical measurements, and for the most part, astronomically: so that it has been rendered possible to delineate the profile above the sea’s level of a tract of land measuring 3,600 miles with all its inflections, extending from the north of Kanzas River to Fort Vancouver and to the coasts of the South Sea (almost 720 miles more than the distance from Madrid to Tobolsk). As I believe I was the first who attempted to represent, in geognostic profile, the configuration of entire countries, as the Spanish Peninsula, the highland of Mexico, and the Cordilleras of South America (for the half-perspective 34projections of the Siberian traveller, the Abbé Chappe,^[O] were based on mere and for the most part on very inaccurate estimates of the falls of rivers); it has afforded me special satisfaction to find the graphical method of representing the earth’s configuration in a vertical direction, that is, the elevation of solid over fluid parts, achieved on so vast a scale. In the mean latitudes of 37° to 43° the Rocky Mountains present, besides the great snow-crowned summits, whose height may be compared to that of the Peak of Teneriffe, elevated plateaux of an extent scarcely to be met with in any other part of the world, and whose breadth from east to west is almost twice that of the Mexican highlands. From the range of the mountains, which begin a little westward of Fort Laramie, to the further side of the Wahsatch Mountains, the elevation of the soil is uninterruptedly maintained from five to upwards of seven thousand feet above the sea’s level; nay, this elevated portion occupies the whole space between the true Rocky Mountains and the Californian snowy coast range from 34° to 45° north latitude. This district, which is a kind of broad longitudinal valley, like that of the lake of Titicaca, has been named The Great Basin by Joseph Walker and Captain Frémont, travellers well acquainted with these western regions. It is a terra incognita of at least 8000 geographical (or 128,000 English) square miles, arid, almost uninhabited, and full of salt lakes, the largest of which is 3940 Parisian (or 4200 English) feet above the level of the sea, and is connected with the narrow Lake Utah,^[P] into which the “Rock River” (Timpan Ogo in the Utah language) pours its copious stream. Father Escalante, in his wanderings from Santa Fé del Nuevo Mexico to Monterey in New California, discovered Frémont’s “Great Salt Lake” in 1776, and confounding together the river and the lake, called it Laguna de Timpanogo. Under this name I inserted it in my map of Mexico, which gave rise to much uncritical discussion regarding the assumed non-existence of a large inland salt lake,^[Q]—a 35question previously mooted by the learned American traveller Tanner. Gallatin expressly says in his memoir on the aboriginal races^[R]—“General Ashley and Mr. J. S. Smith have found the Lake Timpanogo in the same latitude and longitude nearly as had been assigned to it in Humboldt’s Atlas of Mexico.”

I have purposely dwelt at length on these considerations regarding the remarkable elevation of the soil in the region of the Rocky Mountains, since by its extension and height it undoubtedly exercises a great, although hitherto unappreciated influence on the climate of the northern half of the new continent, both in its southern and eastern portions. On this vast and uniformly elevated plateau Frémont found the water covered with ice every night in the month of August. Nor is the configuration of the land less important when considered in reference to the social condition and progress of the great North American United States. Although the mountain range which divides the waters attains a height nearly equal to that of the passes of Mount Simplon (6170 Parisian or 6576 English feet), Mount Gothard (6440 Parisian or 6863 English feet), and the great St. Bernard (7476 Parisian or 7957 English feet), the ascent is so prolonged and gradual that no impediments oppose a general intercourse by means of vehicles and carriages of every kind between the Missouri and Oregon territories, between the Atlantic States, and the new settlements on the Oregon (or Columbia) river, or between the coast-lands lying opposite to Europe on the one side of the continent, and to China on the other. The distance from Boston to the old settlement of Astoria on the Pacific at the mouth of the Oregon when measured in a direct line, and taking into account the difference of longitude, is 550 geographical, i.e., 2200 English miles, or one-sixth less than the distance between Lisbon and Katherinenburg in the Ural district. On account of this gentle ascent of the elevated plains leading from the Missouri to California and the Oregon territory (all the resting-places measured between the Fort and River Lamarie on the northern branch of the Platte river to Fort Hall on the Lewis Fork of the Columbia, being situated at an elevation of from five to upwards of seven thousand feet, and that in Old Park even at the height of 9760 Parisian or 10,402 English feet!), considerable 36difficulty has been experienced in determining the culminating point, or that of the divortia aquarum. It is south of the Wind River Mountains, about midway between the Mississippi and the coast line of the Southern Ocean, and is situated at an elevation of 7490 feet, or only 480 feet lower than the pass of the Great Bernard. The emigrants call this culminating point the South Pass.^[S] It is situated in a pleasant region, embellished by a profusion of artemisiæ, especially A. tridentata (Nuttall), and varieties of asters and cactuses, which cover the micaceous slate and gneiss rocks. Astronomical determinations place its latitude in the parallel of 42° 24′, and its longitude in that of 109° 24′ W. Adolf Erman has already drawn attention to the fact, that the line of strike of the great east-Asiatic Aldanian mountain-chain, which separates the basin of the Lena from the rivers flowing towards the Great Southern Ocean, if extended in the form of a great circle on the surface of the globe, passes through many of the summits of the Rocky Mountains between 40° and 55° north lat. “An American and an Asiatic mountain-chain,” he remarks, “appear therefore to be only portions of one and the same fissure erupted by the shortest channels.”^[T]

The western high mountain coast chain of the Californian maritime Alps, the Sierra Nevada de California, is wholly distinct from the Rocky Mountains, which sink towards the Mackenzie River (that remains covered with ice for a great portion of the year), and from the high table land on which rise individual snow-covered peaks. However injudicious the choice of the appellation of Rocky Mountains may be, when applied to the most northerly prolongation of the Mexican central chain, I do not deem it expedient to substitute for it the denomination of the Oregon Chain, as has frequently been attempted. These mountains do indeed give rise to the sources of three main branches constituting the great Oregon or Columbia river (viz., Lewis’, Clarke’s, and North Fork); but this mighty stream also intersects the chain of the ever snow-crowned maritime Alps of California. The name of Oregon Territory is also employed, politically and officially, to designate the lesser territory of land west of the 37coast chain, where Fort Vancouver and the Walahmutti settlements are situated; and it would therefore seem better to abstain from applying the name of Oregon either to the central or to the coast chain. This denomination, moreover, led the celebrated geographer Malte-Brun into a misconception of the most remarkable kind. He read in an old Spanish chart the following passage:—“And it is still unknown (y aun se ignora) where the source of this river” (now called the Columbia) “is situated,” and he believed that the word ignora signified the name of the Oregon.^[U]

The rocks which give rise to the cataracts of the Columbia at the point where the river breaks through the chain, mark the prolongation of the Sierra Nevada of California from the 44th to the 47th degree of latitude.^[V] In this northern prolongation of the chain lie the three colossal elevations of Mount Jefferson, Mount Hood, and Mount St. Helen’s, which rise 14,540 Parisian (or 15,500 English) feet above the sea-level. The height of this coast chain or range far exceeds therefore that of the Rocky Mountains. “During an eight months’ journey along these maritime Alps,” says Captain Frémont,^[W] “we were constantly within sight of snow-covered summits; and while we were able to cross the Rocky Mountains through the South Pass at an elevation of 7027 feet, we found that the passes in the maritime range, which is divided into several parallel chains, were more than 2000 feet higher”—and therefore only 1170 (English) feet below the summit of Mount Etna. It is also a very remarkable fact, and one which reminds us of the relations of the eastern and western Cordilleras of Chili, that volcanoes still active are only found in the Californian chain which lies in the closest proximity to the sea. The conical mountains of Regnier and of St. Helen’s are almost invariably observed to emit smoke; and on the 23rd of November, 1843, the latter of these volcanoes erupted a mass of ashes which covered the shores of the Columbia for a distance of forty miles, like a fall of snow. To the volcanic Californian chain belong also in the far north of Russian America, Mount Elias (according to La Pérouse 1980 toises, or 12,660 feet, and according to Malaspina 2792 toises, or 17,850 feet in height), and Mount Fair 38Weather (Cerro de Buen Tiempo, 2304 toises, or 14,733 feet high). Both these conical mountains are regarded as still active volcanoes. Frémont’s expedition, which has proved alike useful in reference to botany and geognosy, likewise collected volcanic products in the Rocky Mountains (as scoriaceous basalt, trachyte, and true obsidian), and discovered an old extinct crater somewhat to the east of Fort Hall (43° 2′ north lat., and 112° 28′ west long.), but no traces of any still active volcanoes emitting lava and ashes, were to be met with. We must not confound with these the hitherto unexplained phenomenon termed smoking hills, côtes brûlées, and terrains ardens, in the language of the English settlers and the natives who speak French. “Rows of low conical hills,” says the accurate observer M. Nicollet, “are almost periodically, and sometimes for two or three years continually, covered with dense black smoke, unaccompanied by any visible flames. This phenomenon is more particularly noticed in the territory of the Upper Missouri, and still nearer to the eastern declivity of the Rocky Mountains, where there is a river named by the natives Mankizitah-watpa, or the river of smoking earth. Scorified pseudo-volcanic products, a kind of porcelain jasper, are found in the vicinity of the smoking hills.”

Since the expedition of Lewis and Clarke an opinion has generally prevailed that the Missouri deposits a true pumice on its banks; but here white masses of a delicate cellular texture have been mistaken for that substance. Professor Ducatel was of opinion that the phenomenon which is chiefly observed in the chalk formation, was owing to “the decomposition of water by sulphur pyrites and to a reaction on the brown coal floetzes.”^[X]

If before we close these general remarks regarding the configuration of North America we once more cast a glance at those regions which separate the two diverging coast chains from the central chain, we shall find in strong contrast, on the West, between that central chain and the Californian Alps of the Pacific, an arid and uninhabited elevated plateau nearly six thousand feet above the sea; and in the East, between the Rocky Mountains and the Alleghanies. (whose highest points, Mount Washington and Mount Marcy, rise, 39according to Lyell, to the respective heights, of 6652 and 5400 feet,) we see the richly watered, fruitful, and thickly-inhabited basin of the Mississippi, at an elevation of from four to six hundred feet, or more than twice that of the plains of Lombardy. The hypsometrical character of this eastern valley, or in other words, its relation to the sea’s level, has only very recently been explained by the admirable labours of the talented French astronomer Nicollet, unhappily lost to science by a premature death. His great chart of the Upper Mississippi, executed between the years 1836 and 1840, was based on two hundred and forty astronomical determinations of latitude, and one hundred and seventy barometrical determinations of elevation. The plain which encloses the valley of the Mississippi is identical with that of northern Canada, and forms part of one and the same depressed basin, extending from the Gulf of Mexico to the Arctic Sea.^[Y] Wherever the low land falls in undulations, and slight elevations which still retain their un-English appellation of côteaux des prairies, côteaux des bois, occur in connected rows between the parallels of 47° and 48° north lat., these rows and gentle undulations of the ground separate the waters between Hudson’s Bay and the Gulf of Mexico. Such a line of separation between the waters is formed, north of Lake Superior or Kichi Gummi, by the Missabay Heights, and further west by the elevations known as Hauteurs des Terres, in which are situated the true sources of the Mississippi, one of the largest rivers in the world, and which were not discovered till the year 1832. The highest of these chains of hills hardly attains an elevation of from 1500 to 1600 feet. From its mouth (the old French Balize) to St. Louis, somewhat to the south of its confluence with the Missouri, the Mississippi has a fall of only 380 feet, notwithstanding that the itinerary distance between these two points exceeds 1280 miles. The surface of Lake Superior lies at an elevation of 618 feet, and as its depth in the neighbourhood of the island of Magdalena is fully 790 feet, its bottom must be 172 feet below the surface of the ocean.^[Z]

Beltrami, who in 1825 separated himself from Major Long’s 40expedition, boasted that he had found the sources of the Mississippi in Lake Cass. The river passes, in its upper course, through four lakes, the second of which is the one referred to, while the outermost one, Lake Istaca (47° 13′ north lat., and 95° west long.), was first recognised as the true source of the Mississippi, in 1832, in the expedition of Schoolcraft and Lieutenant Allen. This stream, which subsequently becomes so mighty, is only 17 feet in width, and 15 inches deep, when it issues from the singular horse-shoe-shaped Lake Istaca. The local relations of this river were first fully established on a basis of astronomical observations of position by the scientific expedition of Nicollet, in the year 1836. The height of the sources, that is to say, of the last access of water received by Lake Istaca from the ridge of separation, called Hauteur de Terre, is 1680 feet above the level of the sea. Near this point, and at the southern declivity of the same separating ridge, lies Elbow Lake, the source of the small Red River of the north, which empties itself, after many windings, into Hudson’s Bay. The Carpathian Mountains exhibit similar relations in reference to the origin of the rivers which empty themselves into the Baltic and the Black Sea. M. Nicollet gave the names of celebrated astronomers, opponents as well as friends, with whom he had become acquainted in Europe, to the twenty small lakes which combine together to form narrow groups in the southern and western regions of Lake Istaca. His atlas is thus converted into a geographical album, reminding one of the botanical album of the Flora Peruviana of Ruiz and Pavon, in which the names of new families of plants were made to accord with the Court Calendar, and the various alterations made in the Oficiales de la Secretaria.

The east of the Mississippi is still occupied by dense forests; the west by prairies only, on which the buffalo (Bos Americanus) and the musk ox (Bos moschatus) pasture. These two species of animals, the largest of the new world, furnish the nomadic tribes of the Apaches-Llaneros and Apaches-Lipanos with the means of nourishment. The Assiniboins occasionally slay from seven to eight hundred bisons in the course of a few days in the artificial enclosures constructed for the purpose of driving together the wild 41herds, and known as bison parks.^[AA] The American bison, called by the Mexicans Cibolo, is killed chiefly on account of the tongue, which is regarded as a special delicacy. This animal is not a mere variety of the aurochs of the old world; although, like other species of animals, as for instance the elk (Cervus alces) and the reindeer (Cervus tarandus), no less than the stunted inhabitants of the polar regions, it may be regarded as common to the northern portions of all continents, and as affording a proof of their former long existing connection. The Mexicans apply to the European ox the Aztec term quaquahue, or horned animal, from quaquahuitl, a horn. The huge ox-horns which have been found in ancient Mexican buildings near Cuernavaca, south-west of the capital of Mexico, appear to me to belong to the bison. The Canadian bison can be used for agricultural labour, and will breed with the European cattle, although it is uncertain whether the hybrid thus engendered is capable of propagating its species. Albert Gallatin, who, before his appearance in Europe as a distinguished diplomatist, had acquired by personal observation a considerable amount of information regarding the uncultivated parts of the United States, assures us that the fruitfulness of the mixed breed of the American buffalo and European cattle is an undoubted fact: “the mixed breed,” he writes, “was quite common fifty years ago in some of the north-western counties of Virginia, and the cows, the issue of that mixture, propagated like all others.” “I do not remember,” he further adds, “that full-grown buffaloes were tamed; but dogs would at that time occasionally bring in the young bison-calves, which were reared and bred with European cows. At Monongahela all the cattle for a long time were of this mixed breed. It was said, however, that the cows yielded but little milk.” The favourite food of the buffalo is the Tripsacum dactyloides (known as buffalo-grass in North Carolina) and a hitherto undescribed species of clover allied to the Trifolium repens, and designated by Barton as Trifolium bisonicum.

I have elsewhere^[AB] drawn attention to the fact, that according to a passage of the trustworthy Gomara^[AC], there 42lived, as late as the sixteenth century, an Indian tribe in the north-west of Mexico, in 40° north lat., whose greatest wealth consisted in hordes of tamed buffaloes (bueyes con una giba). Yet, notwithstanding the possibility of taming the buffalo, and the abundance of milk it yields, and notwithstanding the herds of Lamas in the Peruvian Cordilleras, no pastoral tribes were met with on the discovery of America. Nor does history afford any evidence of the existence, at any period, of this intermediate stage of national development. It is also a remarkable fact that the North American bison or buffalo has exerted an influence on geographical discoveries in pathless mountain districts. These animals advance in herds of many thousands in search of a milder climate, during winter, in the countries south of the Arkansas river. Their size and cumbrous forms render it difficult for them to cross high mountains on these migratory courses, and a well-trodden buffalo-path is therefore followed wherever it is met with, as it invariably indicates the most convenient passage across the mountains. Thus buffalo-paths have indicated the best tracks for passing over the Cumberland Mountains in the south-western parts of Virginia and Kentucky, and over the Rocky Mountains, between the sources of the Yellowstone and Plate rivers, and between the southern branch of the Columbia and the Californian Rio Colorado. European settlements have gradually driven the buffalo from the eastern portions of the United States. Formerly these migratory animals passed the banks of the Mississippi and the Ohio, advancing far beyond Pittsburgh.^[AD]

From the granitic rocks of Diego Ramirez and the deeply-intersected district of Terra del Fuego (which in the east contains silurian schist, and in the west, the same schist metamorphosed into granite by the action of subterranean fire,)^[AE] to the North Polar Sea, the Cordilleras extend over a distance of more than 8000 miles. Although not the loftiest, they are the longest mountain chain in the world, being upheaved from one fissure, which runs in the direction of a meridian from pole to pole, and exceeding in linear 43extent the distance which, in the old continent, separates the Pillars of Hercules from the Icy Cape of the Tschuktches, in the north-east of Asia. Where the Andes are divided into several parallel chains, those lying nearest the sea are found to be the seat of the most active volcanoes; and it has moreover been repeatedly observed that when the phenomenon of an eruption of subterranean fire ceases in one mountain chain, it breaks forth in some other parallel range. The cones of eruption usually follow the direction of the axis of the chain; but in the Mexican table-land, the active volcanoes are situated on a transverse fissure, running from sea to sea, in a direction from east and west.^[AF] Wherever the upheaval of mountain masses in the folding of the ancient crust of the earth has opened a communication with the fused interior, volcanic activity continued to be exhibited on the murally upheaved mass by means of the ramification of fissures. That which we call a mountain chain has not been raised to its present elevation, or manifested as it now appears, at one definite period; for we find that rocks, varying considerably in age, have been superimposed on one another, and have penetrated towards the surface through early formed channels. The diversity observable in rocks is owing to the outpouring and upheaval of rocks of eruption, as well as to the complicated and slow process of metamorphism going on in fissures filled with vapour, and conducive to the conduction of heat.

The following have for a long time, viz., from 1830 to 1848, been regarded as the highest or culminating points of the Cordilleras of the new continent:—

The Nevado de Sorata, also called Ancohuma or Tusubaya (15° 52′ south lat.), somewhat to the south of the village of Sorata or Esquibel, in the eastern chain of Bolivia: elevation, 25,222 feet.

The Nevado de Illimani, west of the mission of Yrupana (16° 38′ south lat.), also in the eastern chain of Bolivia: elevation, 24,000 feet.

The Chimborazo (1° 27′ south lat.), in the province of Quito: elevation, 21,422 feet.

The Sorata and Illimani were first measured by the distinguished geologist, Pentland, in the years 1827 and 1838; 44and since the publication of his large map of the basin of the Laguna de Titicaca, in June, 1848, we learn that the above elevations given for the Sorata and Illimani are 3960 feet and 2851 feet too high. His map gives only 21,286 feet for the Sorata, and 21,149 feet for the Illimani. A more exact calculation of the trigonometrical operations of 1838 led Mr. Pentland to these new results. He ascribes an elevation of from 21,700 to 22,350 feet to four summits of the western Cordilleras; and, according to his data, the Peak of Sahama would thus be 926 feet higher than the Chimborazo, but 850 feet lower than the Peak of Aconcagua.