pebbles an inch in diameter; and that a velocity of thirty-six inches per second is requisite to bear away shivery angular stones of the size of an egg. The equatorial currents, leaving the tropics with the highest velocity, yet gradually diminishing towards the poles, would first drop the heavier matters, and afterwards successively the lighter, as its speed decreased. In accordance with this law are the sedimentary elements distributed over the earth. Around the northern portions of the globe, the silurian slates, composed of the lighter clays, everywhere abound. Farther south are the pebbles and sandstones; and as we approach the tropics, the beds of fossil shells, and heavier matters, as well as the alluvium itself, regularly increase in bulk and depth. In New Jersey and Delaware, the beds of loose shells, or shell marl, are wanting, or nearly so; in Virginia they attain a thickness of fifteen feet; in North Carolina, twenty to twenty-five; but in South Carolina they are found from thirty to one hundred feet in depth. This simple law of running water, considered in connection. with the ocean currents, well discloses the source of the sedimentary strata, and satisfactorily establishes that no protracted ages were necessary for their distribution, when so powerful an agent was engaged in the service.

Wherever submarine volcanoes occur, the ocean is seen to boil with violence; scoria of a chocolate color, cinders and dead fish, float upon the surface, and the waters are tinged of a dingy red. In the silurian and carboniferous basins the various strata are vertically interlaced with numerous trap dikes, or veins of lava, which, through narrow fissures, have

been ejected from below, and at times come up to the surface. These, at a former period, or perhaps at different times, were submarine volcanoes, which cemented the matters together and imparted to the sandstones their dingy red color.

Fishes are of very different natures, inhabiting different parts of the watery element. Some remain in the deep and open sea, others in the shallows; some remain permanently in rivers, and others leave the salt water to spend a portion of their time in the continental streams. The herring is a deep-sea fish, of a very prolific nature, taking its name from the German "heer," which signifies an army. It is supposed that they spend their winters in the comfortable regions around the north pole, from whence, in May or June, they visit the coasts of Europe, descending as far as France; and in America, as far as North Carolina. This, however, is only the pioneer force, for about the end of June other great shoals appear towards the extremity of the Shetland Islands, rippling the ocean's surface over a broad extent of many hundred miles. Gulls and gannets, screeching with delight, whales and porpoises, rolling and tumbling, announce their approach, and even the sailors and fishermen aver that their strong oily odor may be detected at a distance. After reaching the Shetland Isles they divide into separate armies, some turning to the eastern coasts of Scotland, Ireland and England, and others taking to the western side, and many, crossing the German Ocean, enter the Baltic. After much shifting and reconnoitering, they at length select the spot where they intend to spawn, and there they remain until the object of their migration is accom

plished, during the winter. All herrings are not alike, even those from the same great shoal that turned to the east, evincing a different development from those on the west. Should one or more of these multitudinous hosts have been passing over or reconnoitering through any of the ancient carboniferous basins, about the time of a submarine eruption, they would at once have been killed, and buried in the drifting sediments. Such a catastrophe would furnish the evidence to sustain the geological statement that the individuals of the primitive ocean were extremely numerous, but confined to the ganoid class. And it would appear, too, as probable, that there were some, or at least one, carnivorous race in the ancient sea; for the tombs of the placoid sharks are significantly near the graves of the ganoid herrings. In such an assemblage as that described, and in that season, we certainly should not expect to find the ctenoid perches or the cycloid salmon; yet at another and later day they came, were surprised and killed in like manner, and were entombed beneath the light snowflake bodies of the insect tribe, then drifting with the current of the seas.

These antediluvian fishes differed from those of the present time in many respects, yet not in such a degree but that they may be accepted as correlatives of each other. This, however, is but reasonable and natural; for if a change of worlds would induce a change in the organization of inhabitants, a change in the climates and conditions of the ocean should equally secure a modification of form in the tenants of the deep. The fossils reveal that this alteration occurred "shortly before man came upon the scene

of action," or, more accurately, before he impressed his footprints upon the present continents. Professor Agassiz is the acknowledged leader in the science of ichthyology, and it is remarkable how accurately and carefully he has read the natures and adaptations of these pristine fishes. True he is impressed with the prevailing idea that the present dry land and seas received the terrestrial and aquatic races as they were created, and that it took untold ages to mould it into its present shape. Yet, notwithstanding, from the peculiar form and organization of the ancient races, he is enabled to see and say, that when they lived there was but little variety among the animals, arising from the peculiar configuration of the globe; that then there were no great mountains, no lofty elevations, nor deep depressions. Between the different zones and continents no such strange contrasts of the different types existed as at the present epoch. The same genera, and often the same species, were found in the seas of America, Europe, Asia, Africa and New Holland, from which we must conclude that the climate was much more uniform than at the present day.*

This page in nature's volume, read by divine light, becomes plain, comprehensible and rational. Through it we learn that, in Noah's day, there occurred a great cataclysm by which the former dry land was changed to sea, and the ancient bed of the sea converted into dry land. Look where we will, over the broad continents, from pole to pole, upon the mountain top, or on the plain, in the deep recesses of the earth, or upon its convex hills, and everywhere this *Principles of Zoology, p. 227.

statement is so thoroughly and clearly affirmed, that he who runs may read it. Physical features and fossils, even the pebbles and alluvial sands, attest the absolute verity of the fact, and by their very position indicate and maintain the potency and adequacy of the power that accomplished the grand conversion. All the parts accord together, and the varied details. combined, present an array of testimony which, in its fullness and completeness, is truly irresistible.

CHAPTER IV.

O Chemistry!

Come with all thy pervading gases,

Thy crucibles, retorts and glasses,

Thy fearful energies and wonders,

Thy dazzling lights and mimic thunders.

H. LUTTREL.

THE parts of the earth's surface that exhibit the primitive rocky crust of the globe, divested of all superficial covering, are comparatively very few and chiefly confined to mountainous and granitic regions. Nearly the whole of our continents are invested with an alluvium, varying in depth, and generally consisting of uncemented sands, gravel, and clays, sometimes separated and arranged in horizontal layers, and at others promiscuously commingled and blended together. The upper portion of this alluvium is denominated the soil, and from it the members of the vegetable kingdom derive all their earthy ele