extensive beds. In its present inaccessible position it gives little prospect of being sought or applied to any useful purpose. Common salt, as before stated, is found along the edges of salt lakes on the Desert. In these situations it is said to be procured with ease by superficial digging, and of very pure quality. For more detailed information in reference to the mineralogical character of the prevaling rocks and earthy deposits, reference may be had to the list of geological specimens, prepared by Professor Hall, of Albany, New York, which will be found in his report. The geographical boundaries of the various formations, with their relative developments, are indicated in the accompanying map and sections. NOTE BY W. H. E. Assistant Arthur Schott passed over the tract of country described in Chapter V. His geological view of it is so similar that I do not consider it necessary to publish it; but I give an extract from his report, which contains some interesting facts in reference to the changes which have taken place in the Great Desert within the historical period, and some general views, which I think are sound, and are applicable not only to the Desert where it is crossed by the Mexican boundary line, but that vast region of desert country which lies to the north of the line, and which spreads out and probably attains its greatest breadth in the region of the Salt Lake. Whatever may be the opinions of persons interested in the more northern lines of travel and projected railway routes to the Pacific, we cannot shut our eyes to the existence of this Desert on any line of travel south of the South Pass, in north latitude 42°. I am also of the opinion that this Desert, within the limits of the United States, is narrower and more easily passed over by a railway immediately north of the Mexican boundary than on any parallel to the north of it. An attentive perusal of the report of Governor Stevens will show that even north of the South Pass vast tracts of arid and desert regions were encountered in the same longitudinal zone, which, added to the rigors of the climate, form an almost insurmountable barrier to the project of opening through those regions any great highway of travel, either by railway or wagon road, between the Atlantic and Pacific States. The full power of the government has been directed towards establishing posts and opening these northern lines of travel; yet we have, within the last few months, seen Fort Laramie, Fort Pierre, and, I believe, even Fort Kearny abandoned by the government, owing to the absolute sterility of the soil, and the impossibility of inducing settlements, or raising even vegetables necessary for the use of the troops. The records of the Quartermaster General's office show the long continued efforts which the government have made to establish these posts as nuclei for settlers, and the utter failure to induce settlement, and make the surrounding country at all conducive to the support of the troops. The idea of carving out States from that portion of the American continent between parallels 35° and 47° and the 100th meridian of longitude and the crest of the Sierra Madre is a chimera. The example of the Mormons is often cited to prove the capacity of the country to sustain population. They occupy an oasis in this great Desert, and their power to sustain even the population they have is by no means established beyond a doubt. On two occasions the grasshoppers were very nearly eating them out and producing a famine; and I am very sure, if it were not for their peculiar institutions, which cannot bear the light of civilization, they could not be induced to remain in their isolated and desert home. We learn from the report of Captain Beckwith, United States army, how very circumscribed is the area of land which is now susceptible of cultivation in the Desert, and the fact that families sometimes go a great distance from the settlements for the advantage of obtaining a few acres of ground susceptible of cultivation. (See page 65, vol. I, Pacific Railroad Report.) When the truth comes to be admitted, I think it will be found that the upper valley of the Rio Bravo, embracing New Mexico and a small portion of western Texas, is the only tract of land, within the limits mentioned in the preceding paragraph, where a body of land is to be found susceptible of sustaining any considerable population. And yet we see, since our occupation of that Territory, in 1846, the population has increased but little, if at all, [EXTRACT FROM REPORT OF ASSISTANT ARTHUR SCHOTT.] TERTIARY SHORE OF THE DESERT. Vallecito, another small Indian settlement in a valley with a number of brackish springs' and abounding in saline soil, is situated on the upper edge of the Desert shore. From Vallecito the road continues along the dry bed of a mountain torrent, deeply filled in with shifting sand. This sand stream seems to form one of the heads of Carrizo Creek, and winds through dreary flats, flanked on both sides by the naked, desolate slopes of the primary and metamorphic mountains. The latter finally cease, and Tertiary ridges, supported by dark masses of eruptive rocks, take their place. These form the real edge of the Desert ocean, which, no doubt, was once the bottom of a wide salt-water basin. The washing of tidal oscillations upon this bold shore caused, probably, the dune-like deposition of the Tertiary hills along the foot of the western Cordilleras. To confirm this supposition of their origin, an isolated group of seabeachloving palms appear to the left of the road, near Carrizo Creek, marking, at the same time, a spot with permanent water. A brief but graphic description of those Tertiary ridges and hillocks has been brought before the public in Major Emory's report of 1848.-(See page 103.) A sketch of these hills is herewith given. VOLCANIC VENTS. Among the Tertiary ridges and hillocks, one may be recognized at once by its singular shape, appearing to be the vent of some volcanic activity now silenced. Major Emory, according to our knowledge, set forth, prior to any other writer, the supposition of the true nature of these hills. After close examination we are able to corroborate the correctness of that supposition. Another not less convincing proof of its neptuno-volcanic origin may be sought in its geographical position, which is upon that long volcanic seam, running north and south, and lining the eastern base of the Peninsular Cordilleras, parts of which are still in activity. VERTICAL SECTION OF AN EXTINCT CRATER IN THE TERTIARY FORMATION, BORDERING THE EAST SLOPE OF THE CALIFORNIAN CORDILLERAS. SOLFATARAS. Some volcanic mud springs or solfataras, to the north, in the Colorado Desert, have been visited by Dr. J. Le Conte, of Philadelphia, in company with Major Heintzelman, Ú. §. A., then commanding officer at Fort Yuma. The former gives an interesting account of his visit there in Silliman's Journal, vol. xix, second series, No. 55, January, 1855. The existence of these springs, however, was not altogether a new discovery of this party, but was well known before to the natives of the country, who resorted to this locality for their annual supply of salt. The other springs, southeast from Carrizo Creek, and not more than twenty miles from the lower Colorado, were visited also, in 1853, by the same officer, accompanied by a small party. The time this officer had chosen for his trip was about three months after a severe shock of an earthquake, which had terrified the inhabitants of those regions on the 29th November, 1852. We are indebted to the liberal kindness of Major J. H. Thomas, the successor of Major Heintzelman, in command of Fort Yuma, for a glance at the manuscripts of the latter. The description of the springs and what was known is, in substance, as follows: "There exists, about forty-five miles below Fort Yuma, in the Desert between the western Cordilleras and the Colorado, a pond, considered as an old orifice, which had been closed for several years." "The first shock of an earthquake, in 1852, caused there a mighty explosion. The steam rose a beautiful snowy jet more than 1,000 high into the air, where it spread high above the mountains, gradually disappearing as a white cloud. "This phenomenon repeated itself several times in a diminishing scale. Three months later I visited the place; jets took place at irregular intervals, from fifteen to twenty minutes. The effect was beautiful, as they rose mingled with the black mud of the pond. The temperature of the water in the principal pond was 118° Fahr., in the smaller one 135° Fahr., and in one of the mud holes, from which gases escaped, 170° Fahr. The air which escaped was full of sulphurated hydrogen, and in the crevices crystals of yellow sulphur were found. The ground near about was covered with a white efflorescence, tinged with red and yellow. On the edge of a small pond crystals of sal ammonia, 1 to 5 inches long, were collected." CLAVIJERO'S ACCOUNTS OF LOWER CALIFORNIA. Other important data bearing upon the geology of Lower California have been brought before the public a long time ago by Clavijero, one of the missionaries in the southern part of the peninsula. He mentions, in his Historia de la Antigua ó baja California, (see Book I, Chapter II,) "two lagoons near the mouth of the Colorado; the red water of the former gave rise to the river's name." The water is described as being very caustic, and so bad that it causes instant swelling and ulcers, accompanied by a burning pain on any part of the body that is brought in contact with it. The effect is said to last for several days. The cause of these bad qualities is likely to be a certain bituminous mineral issuing from the bottom of those lagoons, where some navigators noticed it first in weighing their anchors. Besides these lagoons quite a number of interesting facts are mentioned by the same author.(See Book I, Chapter III, of his work.) Relating to the volcanic character of the shore skirting the base of the Peninsular Cordilleras, the volcano of Mulegé, near 27°, is mentioned. It was discovered in 1746, by the missionaries; but the Spaniards living there made no mention of any eruption or earthquake caused by it. Native sulphur and pummice abound on the slopes and in the vicinity of this mount. A volcanic axis seems to traverse the peninsula from shore to shore, that is, from the mouth of Mulegé River to the Ballena's Bay, where, besides native sulphur, much vitriol occurs. At a place called Kadakaamang, near the Mission of San Ignacio, in latitude 29°, an argillaceous mount is mentioned near the beach. On its slope, about 200 feet above the level of the Gulf, there is a horizontal stratum of fossil shells two feet thick. About seven miles distant from this place a great many fossil oysters are found, some of them being of extraordinary size. One of the missionaries collected some measuring 1 foot 5 inches long, 9 inches broad, and 4 inches thick, and weighing 23 Spanish pounds. It is worthy of notice that here, and in other parts of California, from such fossil shells an excellent lime is prepared. Around the Bay of Mulegé fossil ostrea are recorded to be quite common, especially on a high mountain in the vicinity of the beach. The rocks here are described as exceedingly hard, and well adapted to building purposes. It abounds in fossil shells, which are found imbedded in the innermost strata. It contains also numerous cavities, which seem to have been once occupied by some marine animals now extinct. This certainly proves a submarine formation of the mountain. Rocks of a similar class occur frequently along the whole coast of the Gulf. Seven or eight miles from Loreto, in a locality surrounded by high mountains, is a ridge which is said to consist entirely of layers of fossil shells; similar localities are known to exist more than twenty miles from the Pacific coast, near the Mission of San Luis, on the north side of the Sebastian Viscaino bay. Clavijero thus concludes: "Considering these facts in connexion with the various traces of volcanic activity, and the lar number of islands surrounding the Peninsula, we may imagine what revolutions nature has performed upon this ground. It is, moreover, beyond doubt that the sea has subsided (decrecido) in many places along the coast.' The missionaries of Loreto observed there, during less than forty years, that the tide marks of the sea had receded many yards from the coast, and also that such receding was more perceptible on the west coast. The whole space between the beach and the mountains, a distance of about 26 miles, is deeply overlaid with coast sand (arena litoral.) It is, therefore, evident that the Peninsula in its present configuration has more width now than before our historical era. We may also surely suggest the probability of a continued expansion of the land, until that multitude of islands around California shall be connected with each other and be consolidated finally with the main land. VOLCANISM THROUGH THE GULF BASIN. North of Carrizo Creek the country between the Gulf Basin and the Pacific exhibits perfect congruity of petrographic features. There is, for instance, the Pass San Gorgoño y Bernardino, formed by two huge mountain masses, with an elevation of from 7,000 to 8,000 feet each. Here diluvial deposits form a natural bridge of about two miles in width through that mighty |