The strata of

of the earth must be broken. earth, and rocks above and below the soil, must be examined. There will then be found strata of rocks lying one on another, as books in a pile, and above these various strata of earth, of different colors, consistency, and thickness, as clay of several colors, sand, gravel, &c. The rocks will be found generally in nearly the same order, and yet very frequently exhibiting the appearance of having been operated upon by disturbing forces, throwing them into confusion, breaking, bending, and setting them in inclined planes or perpendiculars; differing in their structure, and composed of various ingredients; some harder, some softer; some fine, some coarse. If a close observer were so situated as to commence his examination near a granite region, and pursue his investigations with diligence, care, and study, his attention would soon be arrested by the appearance of primitive granite, composed of three ingredients thrown promiscuously together-quartz, feldspar, and mica. He would find it deep in the earth, supporting all the other rocks, or breaking up through them in immense irregular masses lying on the mountain's top, and extending to every part of the earth.

It is found in England, Wales, and Scotland, and in different parts of Europe; in the Scandinavian mountains; the Hartz, the range of mountains separating Northern Germany from Bavaria and Bohemia; in the Alps, in Switzerland, and Tyrol; in the Pyrenees, and in the Carpathians. In Asia it is found in the centre of Caucasus; in the Uralian, Himalayan, and Altai mountains, and in Siberia.

In Africa, it appears in Upper Egypt, in the Atlas mountains, and at the Cape of Good Hope, and may be traced along the west parts of North and South America; and it is found in the Southern Islands, and in Australia. So extensive is this rock that it may be almost regarded as the framework of the globe. It will be found to vary in color, hardness, and the magnitude of its grains. On further examination the observer finds a rock composed of the very same materials, but beautifully stratified, and having all the appearance of having been melted to a state of fluidity by great heat, the different parts having united by chemical affinity, and gradually cooled, and become hard. The combined action of heat and water is apparent in the varieties of granite, mica schist, and clay slate, syenite, greenstone, por

phyry, basalt, trachytic-porphyry, and lava, at this day thrown from volcanoes in different parts of the world. Heat especially seems to have acted powerfully in the production of the fluid state in which all unstratified rock originally existed. The power of heat to melt the most solid bodies has been demonstrated by Sir H. Davy, in his numerous and beautiful experiments with voltaic batteries. If we may conjecture, there is probably below all the known rocks, some rocky formation never yet seen by the eye of man; the material of which, operated on by heat, has produced the rocks now known to us as primitive. Water has produced changes on the earth; and various agents, as heat, atmospheric air, wind, and rain, combine their powers to disintegrate the rocks; and the material thus loosened would be carried by wind, rain, and gravitation to the waters which filled the hollows among the rocks. In these operations volcanoes were vastly more common than they are now; and the remains of cooled volcanoes abounding in different parts of the globe, are proof of the fact. Of their existence the various rocks of basalt, greenstone, &c., bear abundant testimony; and their action has produced those protuberances

and subsidences so common on the earth. They did, as they do now, bring up from the interior of the earth various materials for the formation of rocks, crystals, and metals, from great depths, the extent of which we have no means of knowing. Much of those materials may be in a fluid state, and it is almost certain Naples and Sicily must stand over lakes of liquid rocks.

It is most probable that the source of these melted materials is deeply seated beneath the granite. Nevertheless, turbulent and irregular as these operations may appear, they clearly proceed according to the laws of matter and motion, which have ever regulated chemical and mechanical powers; and such is the state of the whole interior of the earth, in the opinion of our best geologists. In sinking artesian wells, it is found that heat increases one degree for every fifty or sixty feet.. If so, a descent toward the centre, of forty-eight miles, would make seven thousand degrees of heat, which is sufficient to convert every material into a melted state; a fluid mass; an ocean of melted rock. This is rendered very probable by the phenomena of volcanoes. The facts connected with their eruptions have been ascertained

beyond a reasonable doubt. The immense masses brought up, and thrown out, in a melted state, leave little doubt that electric and galvanic powers are in energetic action in the interior of the earth; and the rock in a fluid state may remain in a temperature not much greater than melted rock, by the heat being equalized in consequence of the motion of the fluid matter.

Nor are we to apprehend danger from a theory so tremendously terrific, for the crust of the earth being 30, 40, or 50 miles thick, the effect of internal heat would be insensible on the surface on account of the extreme slowness with which it passes through the oxydized rind. Indeed the existence of more than three hundred active volcanoes whose origin is deep-seated in the earth, would appear manifestly designed, in the wisdom and benevolence of God, to prevent the danger resulting from the internal fires, until his own time shall arrive, which in another place we shall endeavor to show may be immensely distant; and as volcanoes appear in all times and periods from the earliest record on the stony books, the library of nature, to have been in action, so they are most probably the necessary vents to