No. 23. A compact, white, feldspathic rock, from the valley of the San Pedro river, in Sonora. Before the blow-pipe it exhibits all the reactions of a felsite or fine-grained porphyry. The texture is compact, resembling the base of porphyry without the crystals. The surface exhibits numerous small cavities, resulting, perhaps, from the decomposition of crystals of feldspar. No. 24. A yellowish pulverulent substance, described by Dr. C. B. R. Kennerly as occurring in a mountain gorge between abrupt walls of volcanic rock. When treated with acid it effervesces strongly, showing the presence of carbonate of lime. After the effervescence has ceased, the residue does not seem to be much acted upon by hot concentrated acids. Before the blow-pipe it fuses with difficulty to a white enamel, owing probably to a combination, at this high temperature, of the silica and lime present. Water takes up from it a considerable quantity of saline matters, consisting of sulphates of lime and magnesia, with traces of chloride of sodium and chloride of potassium. If this be a volcanic ash, as its appearance and mode of occurrence suggest, the presence of the saline matter and carbonate of lime must be attributed to the subsequent action of mineral, probably thermal, springs containing these salts in solution. Very respectfully, yours, JOHN D. EASTER, SMITHSONIAN INSTITUTION, Washington, April 11, 1856. SIR: I have the honor herewith to report the result of my examination of the ores and coals submitted to me for analysis. Those the locality of which is not given belong to the collection obtained by you from a "prospecter," who refused to reveal the precise locality in which they were found. The rest were collected by Mr. A. Schott. No. 1 is a lignite taken from cretaceous strata, covered by trap, at Santa Rosa, Coahuila. The specimen has a brilliant lustre, even fracture, and shows no trace of woody structure. The streak is brown. It is free from pyrites. Fragments of it heated to redness in a closely covered crucible lost 30.45 per cent. of water and bitumen, leaving 69.55 per cent. of coke, which was very porous and had a brilliant metallic lustre. The same specimen completely incinerated yielded 24.22 per cent. of ash. No. 2. Lignite; a dull, lustreless specimen, otherwise quite similar to the preceding. Treated in the same way, it yielded 51.2 per cent. of coke, and 16. 8 per cent. of ash, of a reddish color. No pyrites was observed in it. This No. 3. Lignite; in all respects similar to the preceding. It gave 45.5 per cent. of coke, and 15 per cent. of ash. is the best of these coals. The great amount of ash which these specimens contain renders them of little value as fuel where wood can be had, but in the treeless region where they occur they may be very useful if the beds are extensive and occur at a small depth below the surface; as the specimens were probably taken from the outcrop, it is not unlikely that the seams, when further worked, will improve in quality. No. 4. A lignite from Lake Guzman, in Chihuahua, containing a large proportion of iron pyrites, which, by the action of the atmosphere, has been decomposed and converted into sulphate of iron. It is entirely worthless. No. 5. Water-worn pebbles of red oxide of iron, mixed with much silica, from Los Nogales, near the intersection of the parallel 31° 20′ north latitude, with the 111th meridian. The specimen which I assayed yielded 32 per cent. of iron; the assay was made by Penny's process, with bichromate of potash. No. 6. Two small specimens of red hematite, mixed with specular iron ore and quartz, yielding 37 per cent. of iron. No. 8. Malachite, (carbonate of copper,) enclosing a core of red oxide of copper, containing a few particles of native copper. It yielded 67.76 per cent. of copper. No. 9. Red oxide of copper, containing a considerable proportion of native copper, in threads and crystals. The specimen is created superficially with malachite, and is precisely similar to the ore No. 19, from Boca Grande, described in my former report. It will yield about 95 per cent. of copper. No. 10. A specimen of black oxide of copper, associated with silicate of copper and silica. The mean of two assays gave 50 per cent. of copper. No. 11. Black oxide of copper, mixed with some sulphuret of copper and quartz, from the Sierra Tule, in Sonora. This is very similar to the last specimen. It yielded 57. 66 per cent. of copper. No silver was found in it. No. 12. Red oxide of copper, associated with malachite and small particles of native copper, from the Arizona mines, in Sonora. The mean of two assays gave 74. 96 per cent. of copper. No. 13. A compact silicious ore, containing galena, sulphurets of copper, and arsenical pyrites, intimately mixed with quartz and calcareous spar. It yielded, in an assay conducted in the wet way, 41. 84 per cent. of lead; 0. 12 per cent. silver; and 2.8 per cent. copper. No. 14. Galena, associated with variagated sulphuret of copper, carbonate of lead, and quartz. Very slight traces of silver were detected by hydrochloric acid. The specimen yielded 50. 4 per cent. of lead, and 4 per cent. of copper. I have the honor to remain, very respectfully, yours, JOHN D. EASTER. SMITHSONIAN INSTITUTION, Washington, June 2, 1856. SIR: I have the honor to report herewith the results of my analysis of the mineral water brought by the Boundary Commission from Mier, and of a sedimentary deposit said to be taken from a spring in the same vicinity. The water was contained in two bottles, obtained at different times, one by yourself, the other by Mr. A. Schott. The whole quantity not exceeding one quart, it was impossible to do more than determine the quantity of the more abundant ingredients and the presence of some others. A thorough and minute analysis of a mineral water cannot well be made with less than two to five gallons of water, some of the ingredients being present in exceedingly minute quantities, and yet, doubtless, exerting an important influence on its medicinal properties. The analysis was conducted essentially after Fresenius' method. This water belongs to the class of neutral salines, the most abundant salt being chloride of sodium. Its specific gravity is 1.003. A qualitative analysis proved the presence of the following substances: Silica, iron, alumina, lime, magnesia, soda. sulphuric acid, chlorine, phosphoric acid, iodine, and carbonic acid. It is called a sulphur water, but I could not detect the presence of any trace of sulphuretted hydrogen. It has no reac tion on test paper, and its taste is decidedly saline. The yellow powder (marked No. 25) is a deposit from a chalybeate spring. It was supposed from its color to contain a JOHN D. EASTER. CHAPTER II. SUBSTANCE OF THE SKETCH OF THE GEOLOGY OF THE LOWER RIO BRAVO DEL NORTE. [By Arthur Schott, Assistant Surveyor, U. S. B. C., &c.] SIR In compliance with your instruction, I have the honor to submit to you the following description of the geological features of the country adjoining the Rio Bravo del Norte, from the mouth of the Rio Puerco (Pecos) to the Gulf of Mexico. For the whole extent of country thus designated, I shall use the geological term cretaceous basin of the Rio Bravo, to correspond to the upper basin, which may be properly characterized as the carboniferous metamorphic limestone. Banks of the Rio Bravo del Norte, 2-3 miles above the mouth of the Rio San Pedro, (Texas.) Commencing at the point where the Pecos empties its muddy waters into the Rio Bravo, we find for a distance of about 50 miles a high table-land, consisting of solid masses of hard, dark gray limestone. This formation, viewed in its lithologic character, may be considered as carboniferous; yet the frequent occurrence of fossil remains within its limits hardly admits of its separation from the cretaceous system. The outside of this limestone is, as already stated, of a dark ash color, often rough, prepresenting the appearance that a violently boiling mud-pool would after being upheaved and suddenly cooled. Its inside is often white or pale yellow, and mealy, with a great tendency to disintegration, which causes a great many holes, fissures, and excavations of every shape and description. These give this limestone a peculiar appearance, and one that is remarked by every traveller. VALLEYS. The small, as also the larger, valleys are mostly formed by the continued washing out of the dells and fissures. Thus formed by denudation throughout the whole country, with their borders cracked in every direction, they deserve only the name of deeply cut ravines, (cañons.) This cracked peculiarity may be ascribed to the combined influence of a high temperature, to which this formation may have been at some time exposed, and a subsequent more or less gradual refrigeration. There is scarcely a doubt but that all these table-lands were also formed under the sea, and at the same time exposed to volcanic action. If so, this limestone really deserves the name metamorphic, and its somewhat anomalous appearance would be accounted for. It is our opinion that the limestone of the region above referred to is not of the same character throughout; it is not uniform, and appears under the most variable shapes. It may be seen in various localities, alternating with strata that bear the most striking resemblance to magnesian limestone. STRATIFICATION. The strata of this formation are generally arranged horizontally; sometimes, however, local disturbances appear which placed them into synclinal or anticlinal positions. The lower strata, often being of less solidity than the upper, and readily disintegrating under atmospheric agencies, are finally washed out into excavations by the action of water. These excavations occur commonly in the beds of ravines, and also in the banks of the river as considerable caves. They are also to be seen near the top of the table-lands and hill-ranges, lying as so many terraces, one above the other; the more solid layers, resisting the action of external agencies, project far beyond the softer. High table-lands, intersected with deep vertically walled valleys, characterize the face of the whole country. The walls of these valleys, or more properly speaking, cañons, are variously cracked open, and presenting ravines of greater or less extent in all directions. Those valleys seem to have relation only to the lithologic character of the formation. They are, therefore, usually short, and do not terminate in gradually diminishing fissures, like the heads of rivers and creeks, but suddenly end with a deep chasm under a vertical wall of rock. Deep holes are washed out under these masses of rock, where rain water collects and remains for a considerable time. WATER HOLES. Excavations similar to those here mentioned, and retaining water for some time, occur also in the usually dry beds of the tributaries of the Rio Bravo. This is in most cases the only water that can be procured throughout the arid regions bordering the upper portion of the cretaceous basin of the river. Whilst the running water in these dry beds can find its way only by a subterranean passage through the holes and fissures presented by this formation, pools and small ponds of 150 to 200 feet in length and breadth occur in the cavities formed in the solid masses of rock. The valleys of the rivers Bravo, San Pedro or Devil's river, and Pecos, resemble each other in this respect. BOTTOM-LAND. Soil suitable for cultivation is scarcely seen in these river bottoms. When small slips of it appear, it is confined to places where a projecting rock or a deposit of mud and drift-wood offers some protection against the violence of the currents everywhere present in these rivers. Such patches of bottom-land offer the only shelter and home for the growth of trees, consisting almost exclusively of live oak, hackberry, pecan tree, ash, and some two or three species of rhus. The country embraced by this formation is a waterless region, with a barren and rugged surface. There is but one constantly running tributary of the Rio Bravo between the mouths of the Pecos and San Pedro, a distance of 40 miles. The waters of this tributary, of a blue crystallike transparency, boil out in a deep chasm from beneath a solid mass of limestone, and pour a rapid and full current into the river, but a few paces distant, through dark green shades of flowery and fragrant thickets that line its bed. Its solitary beauty, amid the barrenness and unbroken silence of the surrounding wilderness, suggested a fairy creation, and suggested the name of "Fairy Spring" to this enchanting stream. Other ravines or "rock creeks" afford at times a small stream of clear running water. In their rocky beds occur here and there a series of water holes and small ponds, either isolated or connected only by a trickling run of water. There are several creeks of this character, especially in the vicinity of the Pecos; among which may be mentioned Painted Gallery, Nine-tailed Cat, Oak creek, and Fox-hole. ANTEDILUVIAL DUNES. Groups of hills and low ridges, from 80 to 100 feet in absolute height, appear in different localities on the table land of this region. Fossil remains are found on their slopes, and show that they also belong to the cretaceous formation, and constitute its last link. These hills may be considered as accumulations of cretaceous debris, preceding tertiary strata. The irregularity of the line of their direction, and their unmistakeable parallelism with the water-courses, lead to the conclusion that they really once bordered the submarine currents of a vast cretaceous sea, of which the section of country towards the mouth forms a part. Thus we are able to trace these antediluvial dunes on both sides of the river, and all its tributaries, not only in its upper part, but even as far down as the point where the cretaceous ridges come into view. The Rio San Pedro forms a kind of geological boundary, and seems to have some close relation to other physical peculiarities of the adjoining region. Some changes are here perceptible in the fauna, flora, and meteorology; to speak of which, however, is foreign to the matter in hand. UPPER METAMORPHIC LIMESTONE. The limestone below the mouth of the San Pedro or Devil's river does not form such solid masses as that above. The high table-lands, already described, change into a more rolling, |