tossed and scattered high in the upper regions, but are not calcined by flame. The metallic ores are as various as is the variety of the rocks, enriched by heat and exposed by upheaval and corrosion. No lava, no pumice, no obsidien, nothing of melted matter from the plutonic region is seen. This furrowing of the terrestrial crust has alone occupied and exhausted the stupendous volcanic throes of the subterranean world of fire.

Sierra Mimbres.-The Sierra Mimbres, forming the western envelope of the park, is not dissimilar to the Cordillera in its origin, composition, and configuration. Rising from the level of the great plateau, it is of inferior bulk and rank. It forms the backbone from whose contrasted flanks descend the waters of the Rio del Norte on the east, and of the Colorado on the

west.

Craters of extinct volcanoes are numerous; streams of lava, once liquid, abound; pedrigals of semi-crystalline basalt submerge and cover the valleys into which they have flowed, and over which they have hardened.

This Sierra, then, has a general direction from north to south, corresponding with the 109th meridian. It has all the charac teristics in miniature of the Cordillera, but is chequered and interrupted by the escape of subterranean fires, having areas overflowed and buried beneath the erupted current. Where the nascent springs of the Rio del Norte have their birth, the Sierra Mimbres culminate to stupendous peaks of perennial snow, locally named Sierra San Juan.

The concave plain of the San Luis park, begirt by this elliptical zone of the Sierras, thus capped with a ragged fringe of snow projected upward against the canopy, is the receptacle of their converging waters. It is a bowl of vast amplitude, which has for countless ages received and kept the sedimentary settlings of so prodigious a circuit of Sierras, builded up with every variety of form, structure and geological elements elsewhere found to enter into the architecture of nature. Hither descend the currents of water, of the atmosphere, of lava. The rocks rent from the naked pinnacles, tortured by the intense vicissitudes which assail them; the fragments rolled by the perpetual pressure of gravity upon the descending slopes; the sands and soils from the foundations of rocks and clays of every gradation of hardness; the humus of expired forests and annual vegetation; elements carbonized by transient fires; organic decay; all these elements descend, intermingle, and accumulate.

This concave plain is, then, a bowl filled with sedimentary drift, covered with soil and varnished over as it were with vege tation. The northern department or Rincon, closely embraced by the Sierras and occupied by the San Luis lake, is a vast sa

vanna deposited from the filtration of the waters, highly impreg nated with the mountain debris. Beneath this soil is a continuous pavement of peat, which maintains the saturation of the super-soil, and is admirable for fuel.

The middle region of the plain, longitudinally, displays a crater of the most perfect form. The interior pit has a diameter of twenty miles, from the center of which is seen the circumferent wall forming an exact circle, and in height five hundred feet. This wall is a barranca, composed of lava, pumice, calcined lime, metamorphosed sandstone, vitrified rocks, and obsidien. This circumferent barranca is perforated through by the entrance and departure of the Rio del Norte, the Calebra, and the Costilla rivers, which traverse the northern, western and southern edges of the interior. By this and other forces of corrosion this barranca is on these three sides cut into isolated hills, called cerritos, of every fantastic form and of extraordinary beauty of shape and tints. The bottom of the crater has been filled up with the soils resulting from the decay of this variety of material, introduced by the currents of the water and of the atmosphere. It is beveled by these forces to a perfect level; is of the fattest fertility, and drained through the porous formation which underlies it.

From this crater to its southern rim, a distance of sixty-five miles, the park expands over a prodigious pedrigal formed from it in the period of volcanic activity. This pedrigal retains its level, and is perforated by the the Rio del Norte, whose longitudinal course is confined in a profound chasm or cañon, of perpendicular walls of lava, increasing to the depth of 1,200 feet, where it debouches from the jaws of this gigantic flood of lava, near the village of La Joya, in New Mexico. Such are the extraordinary forms and stupendous dimensions with which nature here salutes the eye and astonishes the imagination. The expansion of the lava is all to the south, following the descent toward the sea. Toward the north, repelled by the ascent, are waves demonstrating the defeated effort to climb the mountain base.

Such is an imperfect sketch of this wonderful amphitheater of the Sierras. Its physical structure is infinitely complex, exhibiting all the elements of nature piled in contact, yet set together in order and arranged in harmony; its cloud compelling Sierras, of stern primeval matter and proportions; its concave basin of fat fertility; its atmosphere of dazzling brilliancy, tonic temperature, and gorgeous tints; its arable and pastoral excellence, grand forests, and multitude of streams; its infinite variety of mines and minerals, embracing the whole catalogue of metals, rocks, clays and fuel; its capacity to produce grain, flax,

wool, hides, vegetables, fruits, meats, poultry, and dairy food; the compact economy of arrangement which blends and interfuses all these varieties; these combine to provoke, stimulate, and reward the taste for physical and mental labor.

Entrance and exit over the rim of the park is everywhere made easy by convenient passes. Roads re-enter upon it from all points of the compass and every portion of the surrounding continent. These are not obstructed at any season. On the north is the Poncho pass, leading to the Upper Arkansas river, and into the south park. On the east, the Mosca and Sangre de Christo passes debouch immediately upon the great plains. On the south is the channel of the Rio del Norte. On the west easy roads diverge to the rivers Chamas, San Juan, and toward Arizona. In the northwest the Cocha-to-pee opens to the great Salt Lake and the Pacific. Convenient thoroughfares and excellent roads converge from all points and diverge with the same facility.

The system of the four parks, extending to the north, indefinitely amplifies and repeats all that characterizes the San Luis park. Smaller in size and less illustrated by variety, each one of the three by itself lingers behind the San Luis, but is an equal ornament in the same family. Their graceful forms, their happy harmony of contact and position, make their aggregated attractions the fascinating charm and glory of the American continent.

Fish,

The abundance and variety of hot springs of every modulation of temperature is very great. These are also equalled by waters of medicinal virtues. It has been the paradise of the aboriginal stock, elsewhere so abundant and various. waterfowl, and birds of game and song and brilliant plumage frequent the streams and groves. Animal life is indefinite in quantity and abundantly various.

The atmospheric currents which sweep away every exhalation and all traces of malaria and miasma have an undeviating rotation. These currents are necessarily vertical in direction and equable in force, alternating smoothly as land and sea currents of the tropical islands of the ocean. The silence and serenity of the atmosphere are not ruffled; the changing temperature alone indicates the motion of nature.

All around the elliptical circumference of the plain, following as it were its shore, and bending with the indented base of the mountain, is an uninterrupted road of unparalleled excellence. This circuit is five hundred miles in length, and is graced with a landscape of uninterrupted grandeur, variety and beauty; on the one hand the mountains, on the other hand the concave plain, diversified with groves of alames and volcanic cerritos. At short intervals of five or ten miles asunder are crossed the

swift-running current and fertile meadows of the converging mountain streams. Hot springs mingle their warm water with all these streams, which swarm with delicate fish and waterfowl.

The works of the beaver and otter are every where encountered, and water power for machinery is of singularly universal distribution. Agriculture classifies itself into pastoral and arable; the former subsisting on the perennial grasses, the latter upon irrigation everywhere attained by the streams and artificial acequias. This concave configuration and symmetry of structure is remarkably propitious in economy of labor and production, favored by the juxtaposition and variety of material, by the short and easy transport, and by the benignant atmosphere. The supreme excellence of position, structure, and productions thus grouped within the system of the parks of Colorado, occupying the heart of the continental home of the American people, is conclusively discernable. Here is the focus of the mountains, of the great rivers and of the metals of the continent. The great rivers have here their extreme sources, which interlock and form innumerable and convenient passes from sea to

sea.

From these they descend smoothly to both oceans by continuous gradations. The parks occupy the line of the fortieth degree, and offer the facilities for a lodgement in force, at the highest altitude, where the highest divide of the continent exists, half way between the trough of the Mississippi and the Pacific shore. Being immediately approachable over the great plains their mines of precious metals are the nearest in the world to the social masses of the American people and to their great commercial cities. Their accessibility is perfect. All the elements of a perfect economy, food, health, geographical position, innumerable mines of the richest ores and every variety, erect, assist, and fortify one another.

The San Luis park has twenty-four thousand population. These people are of the Mexican-American race. Since the conquest of Cortez, A. D. 1520, the Mexican people have acquired and adopted the language, religion, and in modified forms the political and social systems of their European rulers. A taste for seclusion has always characterized the aboriginal masses, heightened by the geographical configuration of their peculiar territory. Upon the plateau elevated seven thousand feet above the oceans, and encased within an uninterrupted barrier of snow, reside nine millions of homogeneous people. An instinctive terror of the ocean, of the torrid heats and malarious atmosphere of the narrow coasts on either sea, perpetually haunts the natives of the plateau. To them navigation is unknown and marine life is abhorrent. The industrial energies of the people always active and elastic, and always recoiling from the sea, have expanded to the north, following the longitudinal direction AM. JOUR. SCI.-SECOND SERIES, VOL. XLIV, No. 132.-Nov., 1867.

of the plateau, of the mountains, and of the great rivers. This column of progress advances from south to north; it has reached and permanently occupies the southern half of the San Luis park.

At the same moment the column of the American people advancing in force across the middle belt of the continent, from east to west, is solidly lodged upon the eastern flank of the Cordillera, and is every where entering the parks through the passes. These two American populations, all of the Christian faith, here meet front to front, harmonize, intermarry, and reinvigorate the blended mass with the peculiar domestic accomplishments of each other.

The Mexican contributes his primitive skill, inherited for centuries without change, in the manipulations of pastoral and mining industry, and in the tillage of the soil by artificial irrigation. The American adds to these machinery and the intelligence of expansive progress. The grafted stock has the sap of both. As the coming continental railroad hastens to bind together our people isolated on the seas, a longitudiual railroad of 2,000 miles will unite with this in its middle course, bisecting the Territory, States and cities of 10,000,000 of affiliated people. This will fuse and harmonize the isolated peoples of our continent into one people, in all the relations of commerce, affinity and concord.

San Louis di Calebra, July 5, 1866.

ART. XXXVIII.-Contributions to the Mineralogy of Nova Scotia; by Prof. O. C. MARSH, of Yale College.-No. 1. Ledererite identical with Gmelinite.

DURING their first geological excursion to Nova Scotia, in 1827, Dr. C. T. Jackson, and the late Francis Alger, Esq., discovered a mineral at Cape Blomidon which has since been the subject of no little discussion among mineralogists.* These authors apparently regarded it from the first as a new species, but other authorities differed widely as to its true nature. Mr. Brooke of London, after measuring the angles of a crystal, pronounced it to be apatite, a view subsequently controverted by M. Dufrénoy of Paris, while Dr. Torrey of New York considered it nepheline.

Dr. Jackson subsequently described the mineral under the name Ledererite, in honor of Baron von Lederer, then Austrian Consul at New York;† and in the same paper Dr. A. A. Hayes, gave the results of an analysis he had made, on which its claims

*Memoirs Am. Acad., vol. i. p. 253.

This Journal, vol. xxv, p. 78.