as to awaken the idea of distant volcanoes; hence I have chosen to call them pseudo-volcanoes

"The smoke from these hills and the crevices in the plastic clay is said to last at the same spot for a long time— say two or three years; indicating at them a large accumulation of combustible materials. It is not, to my knowledge, accompanied by luminous vapors, and is silently wafted along the valley which it mournfully shrouds. The observance of this phenomenon, associated with the frequent recurrence of a peculiar light and spongy stone that the Missouri carries down and strews along its shores, and which has been mistaken for pumice-stone, has led to the often-controverted opinion that there was a volcanic region on the Upper Missouri. There are, however, no true volcanoes over any portion of the United States east of the Rocky Mountains; and it was this belief that led me to the adoption of the word pseudo-volcano. Neither is the substance found in these regions, and commonly called pumice, a true pumice; and, by a similar analogy to that which has prompted the name of its probable origin, I have called it a pumiciform stone (roche pumiciforme).

"Before proceeding to account for the appearances and circumstances attending these smoking hills, I must add a few more facts concerning their traditional and recorded history. There were none in activity when I ascended the Missouri in 1839; and so would seem to have been the case at the passage of Lewis and Clark at the beginning of this century. But, previous to my arrival, since the memorable expedition last referred to, and during a period of three years, they were seen, as my information goes, by many intelligent persons engaged in the fur-trade, all of whom are naturally observant, and most of them of unquestionable authority. I have no doubt, therefore, of the existence of

these hills; and, in truth, upon a distance of 130 miles from Scalp mountain to beyond the Karmichigah, or Great Bend, there is nothing to be seen but a black zone, known to the voyageurs as 'les côtes brulées'-' collines brulées,'-viz: burnt bluffs, or burnt hills.

"In other respects, the character of the vegetation, which is always scant upon this zone, indicates, in a measure, the epochs when it was visited by these subterranean fires; the blacker and more sterile parts being the most recently burnt. They are pointed out by the voyageurs, and I have indicated several on my map. The fossil shells, that I have precedingly enumerated, lose their brilliant opalescent appearance, and are partly calcined, though still preserving their specific distinctions. Layers of the clay are also met with, so altered as almost to deserve the mineralogical name of porcellanite; in fact, all the minerals belonging to the formation exhibit the alteration which might be supposed produced by exposure to that sort of action now to be assigned.

"I believe that these pseudo-volcanic phenomena may be compared with those described as occurring in other portions of the globe, under the name of terrains ardens; although they are not here accompanied by the emission of flames. They are evidently due to the decomposition, by the percolation of atmospheric waters to them, of beds of pyrites, which, reacting on the combustible materials, such as lignites and other substances of a vegetable nature in their vicinity, give rise to a spontaneous combustion; whilst further reactions (well understood by the chemist) upon the lime contained in the clay bed, produce the masses and crystals of selenite that are observed in the lower portion of this interesting deposit. This is the theory which, with some little confidence, we have formed of these pseudo-volcanoes.

"It may be interesting to future travellers to learn that,

in order to collect both fossils and most interesting specimens of crystallized selenite, without taking the trouble of making diggings, it is only necessary to perambulate the zone of plastic clay shortly after it has been washed by heavy rains. Under such circumstances, should they be favored moreover by the reflections of the sun, they will be struck with the appropriateness of the designation of these hills, as applied both by the voyageurs and Indians-namely, of shining mountains. In truth, it is not unlikely that these hills, a portion of them attaining an elevation of from 500 to 700 feet above the river, were some of those referred to by the Sioux of the Missisippi, who, conversing with the first white men who visited them, and long afterwards with Capt. Carver, spoke of the Shining Mountains of the West. "These (so named) pseudo-volcanoes are not, however, confined to the valley of the Missouri. Traces of them are

not unfrequently found over the more westerly regions, as far as the upper portions of the rivers called by the Indians. Mankizitah and Washtey. The name of Mankizitah-watpa, usually translated by that of " White-earth-river" (or simply White river), means, more properly, Smoking Earth river; whence I have concluded that these indications of pseudovolcanoes were at the same time evidences of the recurrence of the upper members of the cretaceous formation, the limit of which I have assigned as being somewhere eastward of the Black Hills. The name of Mauvaises Terres' (bad lands) has been applied to districts cut up into deep and intricate chasms, from which the traveller could hardly hope to extricate himself without the assistance of a good guide, and that are doubtless due to the burning out of their pseudo-volcanoes.

"However this may be, there can be no doubt that the region of country drained by these rivers which I have last

mentioned, will present a wide and fertile field of discovery to any geologist whose good luck it may be to give it a thorough exploration. For there he will find an opportunity not only of studying the continuation of the secondary cretaceous formation previously described, but likewise of discovering the approach to a tertiary formation; the equivalents of which are doubtless to be found to the west of the Rocky Mountains, as they have already been to the east, on the Atlantic borders."

This country is probably one of the most remarkable on the earth, for the variety and abundance of its mineral deposits, and especially for those which are of most extensive use in the arts. The sulphuret of lead occupies about one degree of latitude, extending north from a point on the Missisippi, some eight miles below Galena, and lying on both sides, varying in width till it covers as great an extent from east to west. On the east side of the river the mineral is found principally in a clay matrix, at a depth of sometimes only five or six feet from the surface; on the west side of the river it runs at the depth of one hundred feet or more, overlaid with magnesian limestone. To the south-west of the lead deposit is a very abundant bed of iron, extending from the Maquoqueta River south and west to the Wabesepinicon, in the counties of Jackson and Clinton, in Iowa. The extent of this mineral deposit is not known, but is probably forty miles or more northeast and southwest, with a breadth not less than twenty or thirty miles. The copper region extends north from the lead deposits to Lake Superior. Its precise limits are not known, but it embraces about 300 miles square; it is found south of latitude 43°, in large quantities, and beyond 47° north. From east to west it has an equal extent, being found in situ on Blue Earth river, west of the Missisippi, in 94°, and east as far as

between 88° and 89°. Probably in nearly the whole tract between the Rivers Wisconsin and St. Croix, and the Missisippi and Lake Superior, it is very abundant.

To the south of the lead region, that is, on Rock River, on the east, and south of the Wabesepinicon, on the west of the Missisippi, is a vast bed of bituminous coal (called by Owen the great Illinois coal field), of a good quality, at no great distance below the surface. The country is principally of magnesian limestone formation. The rock is, for the most part, covered with several successive layers of clay, each of the depth of many feet, and is generally not found in digging the wells of greatest depth. At the bluffs of the Missisippi, however, and on some other streams, it outcrops. The superstrata of clay are covered with a pure vegetable mould, unmixed with other matters, of a depth from eight or ten inches to three feet or more. In some localities, as at Iowa City, are deposits of a fine madrepore or encrinitic marble. The country has not yet been explored sufficiently to inform us to what extent these abound, nor how great a variety of minerals it contains. Mineral salt, and saltpetre, are to be considered among them.

The country has about all the varieties of forest trees common to the same latitudes on this continent; including five or six species of oak, the walnuts, ashes, maples, elms, hickories, locusts, mulberries, aspens, and poplars, one variety of which is very abundant, known as the cotton wood, &c. There are very few birches, and the writer has not seen any beeches or chestnuts. Of wild plums, the varieties are almost endless; many of them are good, some nearly equal to the best cultivated plums, some indifferent. Ironwood is abundant on the bottoms.

The prickly ash, hawthorn, grape, and gooseberry, are among the shrubs and vines. The vegetation is not only