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existence of animal or vegetable organization, to the secondary, which contain the organic remains of generations passed away, and which have been termed the medals of nature to the tertiary which was last produced, and the alluvia that is daily deposited at the present.

We have also noticed the causes now operating, and changing the surface of our planet, viz. the action of the elements, water more particularly. and the formation of peat and of coral reefs, and have examined the agency of volcanoes and earthquakes. And in so doing, have superficially traced the outlines of geological science. The description and history of the various mineral contents of rocks do not come within my duties, but belong to mineralogy.

Should I be asked for a book of reference containing the elements of geology, I must answer that I know of no work that is fit for a beginner in the study. Humboldt, Macculloch, Conybeare and Phillips, and Bakewell, all presuppose too muchand are calculated for the perusal of geologists, rather than students. Their works however may be advantageously consulted. The various periodicals of the United States contain more or less information on this subject-among others I cannot refrain from noticing a little and unpretending pamphlet

occasionally published. "The Annals of the Lyceum of Natural History, of New-York," a society that is actively and honorably engaged in examining and elucidating the natural history of our country, Nor can I omit to mention the Journal of the Academy of Natural Sciences of Philadelphia: Nor the American Journal of Science, so ably conducted by Prof. Silliman.

I am as sensible as any of you can be of the deficiencies and imperfections of this course: but I make no apology, conscious of your being all aware, that no subject, no scientific subject, can be properly treated of and condensed into four or six lectures.

We might have passed our hours with more amusement, but then we must necessarily have departed from the dry detail of this science.

I regret that more time was not allowed to enlarge upon and illustrate the real value and utility of this science. And if in my Lectures I have failed to render the study of Geology interesting, I have the candor to acknowledge, and sincerely wish you all to believe, that the fault lies not in the subject, but in the person who has the honor to address you.

To facilitate the study of Geology, a Synopsis of each individual Rock is here added, affording a view of the different compounds that may be classed respectively under each head.

SYNOPSIS OF GRANITE.

First Division.

Of two ingredients.

A. Felspar and mica.

B. Quartz and felspar.

a. An uniform mixture of these ingredients. b.. The quartz, or felspar, or both, imperfectly crystallised, and influencing each other's forms. Graphic granite.

C. Quartz, and hornblende.

D. Felspar and hornblende.

a. Large grained, or the hornblende crystallised. b. An uniform granular mixture: the ingredients varying materially in their sizes and proportions.

c. Intimately mixed, so as to be nearly undistinguishable.

Second Division.

Of three ingredients.

A. Quartz, felspar and mica.

a. An uniform mixture of the ingredients.

b. The same with additional crystals of felspar embedded, porphyritic granite.

c. With two kinds of felspar, the common and glassy.

d. The quartz, or the felspar, or the mica, or all of them crystallised.

B. Quartz, felspar and hornblende.

a. Large grained. The sienite of some mineralogists.

b. Small grained, and, like D. b. div. 1st, often resembling the greenstones of the trap family, by which name some mineralogists have also distinguished it.

C. Quartz, felspar and actynolite.
D. Quartz, felspar and chlorite.
E. Quartz, felspar and talc.

F. Felspar, hornblende and mica.

This variety occurs in the same manner as D. div. 1st, but is rare.

Third Division.

Of four ingredients.

A. Quartz, felspar, mica, and hornblende: the

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