No geological phenomenon more strikingly evinces the wisdom of the arrangements of Providence, than the beds of rivers. The blood, propelled by the heart through the arteries to the extremities, and there taken up by the veins and carried back to the heart to circulate in the perpetual circle of life, shows no more striking manifestation of the wisdom of Providence, in the economy of the human body, than the configuration of countries, by which they are at once watered and drained, in the structure of the globe. The earth offers no more striking example of this configuration, than the valley of the Mississippi. Suppose at one time we contemplate this valley from the Alleghanies, and at another from the Rocky Mountains, at the remotest headspring of the Missouri. Let us trace the thousand rivers that rise in these mountains and flow down their eastern slope; and, in the other position, attempt to number all the streams that flow to the same point from the west. What hand, we shall ask in astonishment, but one guided by infinite design, could have scooped out such an exact basin, with such a perfectly graduated inclination, that each spring has its valley, each stream its basin, every river its narrow dividing ridge, operating as an arranged inclined plane to drain every portion of its slope. This complicated tissue of arteries and veins circulates the indispensable irrigating fluid to the main channel of the trunk, which rolls its accumulating waters downward to the sea, to return, as we have seen, by the clouds, and circle through the same channels, producing the same beneficent results again. In the more elevated regions, you stand on the dividing ridge of the great rivers. Springs gush from under the cliffs, as you look towards the rising sun. They trickle along their appointed bed, tribute still added to tribute, until they form a river that rolls into the Atlantic. You turn your face towards the setting sun, descend the declivity a few steps, and drink from the fountain that flows in an opposite direction, and finds its way at the distance of eight hundred leagues from the estuary of its neighboring spring, into the gulf of Mexico.

Who established these accurate and narrow barriers, and graduated these vast extents with such an exact slope, that a gentle and equable declivity is furnished for the waters through all the long course of their passage? The slightest mistake in the inclination of the plane, would have turned all these streams back upon their source, and the vast extent of fertile valleys would have become the steaming and pestilential surfaces of lakes and uninhabited marshes.

Contemplate the same unerring wisdom of foresight in the continuous lines of high hills and cliffs, that form the everlasting bulwarks of all the great and sweeping rivers in their whole courses. This wonderful spectacle cannot fail to impress every observing traveller, as he is conveyed on these rivers. The battlements that are raised along the courses of North River, the Susquehannah, Potomac, and particularly the long channel of the Ohio, Tennessee, Cumberland, Mississippi, and Missouri, to confine them to their beds and prevent their inflicting desolating inundations, cannot but arrest the most careless attention. One cannot note these lines of bluffs, as long as the courses of their rivers, and extending in an uninterrupted line a thousand leagues, and opposing such ample and irresistible barriers to the waters, without looking through those second causes by which some geologists would account for them to the ultimate cause, the purpose of the Creator, the secure habitancy of these valleys by men; or fail to be convinced that the riverchannels were formed for the draining and the irrigation of the country; and that the configuration of the surface, to convey all the waters requisite for irrigation through the country in channels, was alike arranged to subserve the purposes of beauty, safety, and utility. So far as second causes are concerned in this admirable configuration of the country, I see no solution more adequate to account for the digging these long channels, and arranging these admirable slopes, than the deluge. Whatever cause may have produced the emersion of the continents from the ocean, the waters flowing off towards their ocean-beds, would find by the action of their own laws precisely such places as are their present

channels, and in the lapse of ages would cut them down and denude their bluffs, as we now see them.

It needs no elaborate reasonings, to prove that the Alleghanies, the Rocky Mountains, and the whole vast sweep of hills that mark the outer rim of the Mississippi Valley, are wearing away, and the debris constantly deposited in the valleys of the rivers, or borne down to the gulf of Mexico. The recession of the sea, the gradual encroachment of the Florida and Louisiana shore upon it; the waters of the Mississippi, turbid with as much earth as they can hold in suspension, distinguishable by their ashy color, for many leagues from its mouth; the increasing number of shoals and bars where these deposits are precipitated, are conclusive proofs that the earth is gaining fast upon the sea in that quarter. This gain must be an equal loss to the country, through which the rivers flow. The same may be predicated of the valleys of all the other rivers of the globe.

Whence happens it, that in the lapse of so many thousand years, every particle of earth has not been washed away from the mountain and hill sides; and that the mountains and hills have not, ages since, presented the spectacle of naked skeletons of everlasting rock? Such is not the fact. Many of the steepest hill and mountain-sides, washed by every rain, are still covered with thick layers of the richest and most friable vegetable mould. It seems to me, that nature has some arrangement of compensation not yet explained or understood, by which, in her own way, she repairs and renews this detritus of her slopes, borne away by the rivers. I neither adopt the rough-cast creed of the hunter, that the mountains and hills grow as fast as they are washed away; nor the transcendental theory, that they repair their losses by receiving supplies of consolidated sun-beams, radiated into their substance. I only see, that the hills and mountains load the rivers with detritus, without seeming to lose by the tribute borne from them from age to age.

La Place has demonstrated, that what had been formerly set down as an aberration of our planet, the apparent change of its orbit, as marked by the precession of the equinoxes, a

change which some astronomers had predicted would eventually destroy our system, instead of being an evidence of a principle of destruction, is really a result of the settled order of the universe, and that, not to have been subjected to this law, would have been evidence of aberration and tendency to decay.

The views which I take of the phenomena of our world, convince me, if no other person, that by the operation of laws contained in itself, all the changes which the earth is undergoing are changes for the better, and harmonies in stead of symptoms of decline; and that the ultimate tendency is, to cause it to become a more convenient and happy abode for its sentient inhabitants of every description.

Another deluge would change its surface. Volcanic eruption or earthquake, of a terrible energy to cause the centre to become the circumference, would annihilate no particle of its matter. Were it even heated by a comet to ignition and vitrification, the mass would change its form without annihilating it, or weakening its subservience to its physical laws in the slightest degree. The combustion of fuel, every one now knows, destroys nothing of the substances of which it was composed, but only separates it into its constituent elements, the amount of matter remaining precisely the same.

In this lecture I shall present tabular views of some of the more prominent doctrines and terms of geology, chiefly compiled from Bakewell's introduction to the study. The elementary principles of geology were deduced from discovering, that wherever the earth was deeply perforated, it discovered surprisingly regular crusts, or integuments, which have been familiarly illustrated by comparing them to the different coats of an onion, or to the successive coats of paint laid upon an artificial globe. The deepest of these integuments is composed of rocks extremely hard and semicrystalline, called granite. These rocks are called primary, because they contain neither the organic remains of animals, nor vegetables, nor intermixtures of other rocks. Their substance seems uniform, and not compounded with the rocks that lie above them. They are common on the highest summits of mountains.

On other summits, these rocks are covered with superincumbent strata of another character, and the granite belt shows itself only at the basis of the mountains. A belt of this kind of rocks, in the United States, generally skirts the northern sea shore, the northern shores of the great lakes, and certain summits of the Rocky Mountains, where they are visible upon the surface. Boulders, or masses of this kind of rocks, are found detached from their natural position, apparently by some of the changes which the earth has evidently undergone, in the Mississippi Valley. These masses are scattered among limestone and other rocks of secondary formation, far from points where granite is found in its native position. A crust of this kind of rocks, at certain depths, probably encompasses the whole globe.