Charles Lyell eBooks

Principles of Geology: Being an Inquiry How Far the Former Changes on the Earth's Surface Are Referable to Causes Now in Operation. E-book. Formato PDF Charles Lyell   -  Forgotten Books, 2017  - 

In the Preface to the former edition of the "Principles of Geology," I gave a brief account of the progress of the work up to the publication of the Third Volume in 1833. This account I shall now repeat with some omissions, and with the addition of such information as I think will be useful to the reader respecting the latest alterations made in the work.The original MS. of the "Principles of Geology" was delivered to the publisher at the close of the year 1827, when it was proposed that it should appear in the course of the year following, in two volumes octavo. Many causes concurred to delay the completion of the work, and considerably to modify the original plan. In May, 1828, when the preliminary chapters on the History of Geology, and some others which follow them in the first volume, were nearly finished, I became anxious to visit several parts of the continent, in order to acquire more information concerning the tertiary formations.

The Student's Elements of Geology. E-book. Formato PDF Charles Lyell   -  Forgotten Books, 2017  - 

The last or sixth edition of my Elements of Geology was already out of print before the end 'of 1868, in which year I brought out the tenth edition of my Principles of Geology. In writing the last-mentioned work I had been called upon to pass in review almost all the leading points of specula tion and controversy to which the rapid advance of the sci ence had given rise, and when I proposed to bring out a new edition of the Elements I was strongly urged by my friends not to repeat these theoretical discussions, but to confine myself in the new treatise to those parts of the Ele ments which were most indispensable to a beginner. This was to revert, to a certain extent, to the original plan of the first edition; but I found, after omitting a great number of subjects, that the necessity of bringing up to the day those which remained, and adverting, however brie?y, to new dis coveries, made it most difficult to confine the proposed abridgment within moderate limits. Some chapters had to be entirely recast, some additional illustrations to be intro duced, and figures of some organic remains to be replaced by new ones from specimens more perfect than those which had been at my command on former occasions. By these changes the work assumed a form so different from the sixth edition of the Elements, that I resolved to give it a new title and call it the Student's Elements of Geology. In executing this task I have found it very difficult to meet the requirements of those who' are entirely ignorant of the science. It is only the adept who has already overcomexiv preface.

Elements of Geology. E-book. Formato PDF Charles Lyell   -  Forgotten Books, 2017  - 

By the earth's crust, is meant that small portion of the exterior of our planet which is accessible to human observation. It comprises not merely all of which the structure is laid open in mountain precipices, or in cliffs overhanging the river or the sea, or whatever the miner may reveal in artificial excavations; but the whole of that outer covering of the planet on which we are enabled to reason by observations made at or near the sur face. These reasonings may extend to a depth of several miles, perhaps ten miles; but even then it may be said, that such a thickness is no more than I%3th part of the distance from the surface to the centre. The remark is just; but although the dimensions of such a crust are, in truth, insignificant when com pared to the entire globe, yet they are vast and of magnificent extent in relation to man, and to the organic beings which peo ple our globe. Referring to this standard of magnitude, the geologist may admire the ample limits of his domain, and admit, at the same time, that not only the exterior of the planet, but the entire earth, is but an atom in the midst of the countless worlds surveyed by the astronomer.