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same time appending such details as might render the volume an acceptable Handbook of Reference to the student and professed Geologist. Thus the ordinary reader will generally find the information he requires in the first and second sentences of a definition ; what follows is addressed more especially to the professional inquirer—to the student, miner, engineer, architect, agriculturist, and others, who may have occasion to deal with geological facts, and yet who might not be inclined to turn up half-a-dozen volumes, or go through a course of geological readings, for an explanation of the term in question.

Such is the aim and object of this “Handbook of Geological Terms." I lay claim to little more than the arrangement of the matter, which has been gleaned and sifted from many sources—care having always been taken to present the science in its newest aspects, and to express its facts in the clearest and simplest language. Sensible of many imperfections, I would respectfully solicit corrections from those who may generally approve of the work, in order that any subsequent edition may be rendered more worthy of the Science whose truths we are labouring to establish—a science which, whether intellectually or economically considered, stands second to none on the roll of human acquirements.

D. P.

GILMORE PLACE, EDINBURGH,

August 1859.

SECOND EDITION

In preparing this edition, alterations rendered necessary by the progress of the science have been freely made, and the more important terms introduced by recent discovery extensively inserted. To have inserted all or nearly all would have increased the volume beyond the limits of a “Handbook," and merely cumbered its pages with names, a great proportion of which are avowedly provisional, and many even of doubtful validity. As a new feature, the leading technicalities of Physical Geography have been given along with those of Geology—the Author believing that the two sciences are inseparably associated, and that the readiest way to a comprehension of the world's past is through the study of its existing phenomena.

August 1865.

CONTENTS

TABULAR SCHEMES OF THE CHEMICAL, MINERAL, LITHOLO-

GICAL, AND VITAL ASPECTS OF THE GLOBE.

EXPLANATION OF SPECIFIC APPELLATIONS MADE USE OF

BY BRITISH AND FOREIGN PALÆONTOLOGISTS.

NOTE. — “It is, indeed,” says Agassiz, in his recent 'Essay on Classification,' "a very unfortunate tendency, which prevails now almost universally among naturalists, with reference to all kinds of groups, of whatever value they may be, from the branches down to the species, to separate at once from one another any types which exhibit marked differences, without even inquiring first whether these differences are of a kind that justifies such separations. In our systems, the quantitative element of differentiation prevails too exclusively over the qualitative. If such distinctions are introduced under well-sounding names, they are almost certain to be adopted; as if science gained anything by concealing a difficulty under a Greek or Latin name, or was advanced by the additional burden of a new nomenclature. Another objectionable practice, prevailing quite as extensively also, consists in the change of names, or the modification of the extent and meaning of old ones, without the addition of new information or of new views. If this practice is not abandoned, it will necessarily end in making Natural History a mere matter of nomenclature, instead of fostering its higher philosophical character.” Influenced by this opinion, I have adopted in the following tabulations such arrangements of the Mineral, Vegetable, and Animal kingdoms as have been sanctioned by our leading naturalists—which appear to be most intelligible to the general reader—and on which, indeed, the greater portion of the nomenclature of Geology and Palæontology has been founded.

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