Transcriber Note Text emphasis denoted as _Italics_ and =Bold=. Whole and fractional numbers as 123-4/5. The Cambridge Manuals of Science and Literature ROCKS AND THEIR ORIGINS CAMBRIDGE UNIVERSITY PRESS =London:= FETTER LANE, E.C. C. F. CLAY, Manager [Illustration] =Edinburgh:= 100, PRINCES STREET =London:= WILLIAM WESLEY & SON, 28, ESSEX STREET, STRAND =Berlin:= A. ASHER AND CO. =Leipzig:= F. A. BROCKHAUS =New York:= G. P. PUTNAM'S SONS =Bombay and Calcutta:= MACMILLAN AND CO., Ltd. _All rights reserved_ ROCKS AND THEIR ORIGINS BY GRENVILLE A. J. COLE Professor of Geology in the Royal College of Science for Ireland Cambridge: at the University Press 1912 =Cambridge:= PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS _With the exception of the coat of arms at the foot, the design on the title page is a reproduction of one used by the earliest known Cambridge printer, John Siberch, 1521_ PREFACE