A Selection of Geological Memoirs Contained in the Annales Des Mines - Softcover

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1836. Excerpt: ... 'On the relative position of the Serpentines ( Ophiolites ), Diallage Rocks (EuphotidesJ, Jasper, 8gc. in some parts of the Apennines; by Alexander Brongniart, Member of the Royal Academy of Sciences, Sgc. fyc. Read at the Royal Academy of Sciences, December 6, 1820. (Annales des Mines for 1821). Introduction. IT is now very generally agreed that the end of positive Geology is to be able to understand, as exactly and completely as possible, the nature and structure of the crust of the globe, and to discover if general and constant laws have, governed this structure. The precise determination of the rocks, minerals, and fossil organic bodies constituting the different portions of this crust, and lastly that of their relative position, are the principal and perhaps only means that can enable us to acquire this knowledge, and lead us to the general, interesting and useful results that it promises. All geologists are agreed on these three propositions, and all endeavour to discover by different means the order of superposition of formations and the rocks composing them; but all are not yet equally agreed on the utility on determining previously, and independently of every other consideration, the rocks entering into the structure of formations. Some, without altogether rejecting this mode of considering thetn, attach L very little importance to it; others, confounding it with the state of relative positions (positions respectives), desire that mineralogical descriptions should constantly accompany those of the formations. We have for a long time exerted our efforts to prove that these two subjects ought to be separately treated, that their confusion is necessarily carried into the science and retards the progress of it; we have with pleasure seen these princi...