Every appearance seems to warrant the conclusion that these impressions were made at a time when the rock was soft enough to receive them by pressure, and that the marks of feet are natural and genuine. ‘Such was the opinion of Governor Cass and myself,’ says Mr. Schoolcraft, ‘formed upon the spot, and there is nothing that I have subsequently seen to alter this view: on the contrary, there are some corroborating facts calculated to strengthen and confirm it.’ At Herculaneum, in the same neighborhood, similar marks have been found, as well as on some of the spurs of the Cumberland mountains, always in similar limestone. In the latter case it is stated that the impressions are elongated, as of persons slipping in ascending a slimy steep. Opinions are much divided as to the origin and import of these impressions. Should similar observations multiply, important inferences may perhaps be drawn from them; at present it seems impossible to speak respecting them decisively or satisfactorily.
The following extraordinary facts, respecting what may be termed living fossils, appear to be well authenticated. During the construction of the Erie canal, while the workmen were cutting through a ridge of gravel, they found several hundred of live molluscous animals. ‘I have before me,’ says Professor Eaton, ‘several of the shells from which the workmen took the animals, fried and ate them. I have received satisfactory assurances that the animals were taken alive from the depth of forty-two feet.’ In addition to this discovery in diluvial deposits, mention is made of a similar one in a much older formation. In laying the foundation of a house at Whitesborough, the workmen had occasion to split a large stone from the millstone grit. ‘It was perfectly close-grained and compact. On opening it, they discovered a black, or dark brown spherical mass, about three inches in diameter, in a cavity which it filled. On examining it particularly, they found it to be a toad, much larger than the common species and of a darker color. It was perfectly torpid. It was laid upon a stone, and soon began to give signs of life. In a few hours, it would hop moderately on being disturbed. They saw it in the yard, moving about slowly for several days; but it was not watched by them any longer, and no one observed its farther movements. They laid one half of the stone in the wall, so that the cavity may still be seen.
‘The millstone grit,’ says Professor Eaton, who gives this account, ‘in which this toad was found, is the oldest of the secondary rocks. It must have been formed many years before the deluge. Was this toad more than four thousand years old? or was it from an egg introduced, through a minute and undiscovered cleavage, into this cavity or geode, made precisely to fit the size and form of a toad? I was particular in my inquiry, and learned that the whole stone was perfectly compact, without any open cleavage which would admit an egg. Besides, it is well known that the millstone grit is neither porous nor geodiferous. If this rock stratum was deposited upon the toad, it must have been in aqueous, not in igneous solution,and the toad must have been full grown at the time. Toads are often found in compact, hard, gravelly diluvial deposits, in situations which demonstrate that they must have lived from the time of the deluge. I think I am warranted in saying this without citing authorities, as it is a common occurrence. Then why may they not have lived a few centuries longer, if we admit them a life of at least three thousand years?’
GENERAL REMARKS ON GEOLOGY.
Geological researches are made with much greater facility in America than in Europe, especially in the region of the secondary strata. The immense extent over which they can be traced, the undisturbed condition in which they are found, and their generally horizontal position, afford great facility for efforts of system and generalization. The absence of the newest floetz-trap rocks, and of the effects of the violent convulsions, so frequent in the vicinity of this disputed formation, unquestionably assist geological research. A second and more efficient cause is found in the extent of the changes that have been wrought in the different classes of rocks on the European continent since their original formation, by the effect of water, and the continual action of rivers wearing deep beds, and exposing the subordinate strata. Rivers also in North America have not generally cut so deep into the different strata, either in the mountains, or during their course in the level country, as materially to derange the stratifications. Broken masses of one formation covering the tops of mountains, whose foundations are composed of rocks of a different class, seldom occur. A third cause of the facility of geological observation in this continent is found in the fact that the whole continent east of the Mississippi follows the arrangement of one great chain of mountains. Europe, on the contrary, is intersected by five or six distinct ranges, which follow different laws of stratification, and frequently interrupt each other.
The effect of opening this new field of observation has been striking and important. It has been to confound every previous effort at the determination and arrangement of general strata. European geologists themselves have acknowledged that the general strata must be determined in America. The absence of the chalk forcibly illustrates this; the chalk being not only a very prominent feature in the geological structure of Europe, but the grand point of division between the secondary and tertiary formations. The English oolite is not found in this country. It has been affirmed by Professor Eaton that the old red sandstone is not a general stratum, and even the existence of primitive clay-slate is questioned; while Mr. Maclure informs us that though the primitive formation contains all the variety of rocks contained in the mountains of Europe, yet neither their relative situation in the order of succession, nor their relative heights in the range of mountains, correspond with European observations. The order of succession from the clay-slate to the granite, as well as the gradually diminishing height of the strata, from the granite through the gneiss, mica slate, and hornblende rock, down to the clay-slate, is so often inverted and mixed, as to render the arrangement of any regular series impracticable.
It is of course out of the question in these remarks to present a detailed account of the general science of geology. For valuable and well-digested treatises on this subject, we refer to Cuvier’s Theory of the Earth, and Lyell’s Principles of Geology. The volumes of Silliman’s Journal, and Professor Cleaveland’s works, abound in important matter on the geology of our continent.
CHAPTER XIX.—NATURAL CURIOSITIES.
It is our intention to collect under this general head a few miscellaneous descriptions, that could not have been properly placed under any other division. The space that we can devote to this subject is small, and it is impossible to enter into much detail. Among the most admired and interesting natural curiosities of our country, are the Pictured Rocks, of lake Superior, which have been described by an intelligent traveller to whose observation we have been already largely indebted.