Dismissing from his mind all preconceived opinions, the student must be prepared to learn that the earth's surface has been, and still is, subject to perpetual mutation,--that the sea and land are continually changing place,--that what is now dry land was once the bottom of the deep, and that the bed of the present ocean will, in its turn, be elevated above the water and become land,--that all the solid materials of the globe have been in a softened, fluid, or gaseous state,--that the relics of countless myriads of animals and plants are entombed in the rocks and strata,--and that vast mountain-chains, and extensive regions, are wholly composed of the petrified remains of beings that lived and died in periods long antecedent to the creation of the human race. Astounding as are these propositions, they rest upon evidence so clear and incontrovertible, that they cannot fail to be admitted by every intelligent and unprejudiced reader, who will bestow but a moderate share of attention to the examination of the phenomena, of which the following pages present a familiar exposition. I cannot conclude these introductory observations, without adverting to the incalculable benefits which result from scientific pursuits in general, and of Geology in particular. An able modern writer has justly remarked:--"It is fearfully true, that nine-tenths of the immorality which pervades the better classes of society, originate from the want of an interesting occupation to fill up the vacant time; and as the study of the natural sciences is as attractive as it is beneficial, it must necessarily exert a moral and even religious influence upon the young and inquiring mind. The youth who is fond of scientific pursuits will not enter into revelry, for frivolous or vicious excitements will have no fascination for him. The overflowing cup, the unmeaning or dishonest game, will not entice him. If any one doubts the beneficial influence of these studies on the morals and character, I would ask him to point out the immoral young man who is devotedly attached to any branch of natural science: I never knew such an one. There may be such individuals--for religion only can change the heart--but if there be, they are very rare exceptions; and the loud clamours which are always raised against the man of science who errs, prove how rarely the study of the works of the Creator fails to exert an ennobling effect upon a well-regulated mind. Fortunate, indeed, are the youth of either sex, who early imbibe a taste for natural knowledge, and whose predilections are not thwarted by injudicious friends."