Ban goc (Tiếng Anh)

PREFACE. 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 speculation and controversy to which the rapid advance of the science had given rise, and when I proposed to bring out a new edition of the “Elements” I was strongly urged by my friends not