
PREFACE TO THE FIRST EDITION aii 
photographs reproduced on Plates XXV. and LIV., which were 
taken on one of the excursions of my Summer Class. Mr 
Francis J. Lewis, of the University of Liverpool, whose 
investigations into the structure and history of the peat-bogs 
of Britain promise to be of the greatest interest and import- 
ance to botanists and geologists, kindly put at my disposal 
several characteristic photographs of peat-bogs, from which I 
selected the illustration that appears in Plate LIV. Unless 
when otherwise stated, all the other Plates are reproductions 
from photographs of specimens in my own Class-Museum, 
taken under the superintendence of Dr J. D. Falconer, formerly 
my assistant and now Director of the Mineral Survey of 
Northern Nigeria. I may add that many of the illustrations 
in the text were drawn for me by my son, Mr W. Cranston 
Geikie. 
EDINBURGH, April 15, 1905. 
meee Acre FrO-THE SECOND EDITION 
THIS edition differs but little from its predecessor. The 
author has taken the opportunity it has afforded him, however, 
to supply some omissions, and to make a number of emenda- 
tions and corrections, which he hopes may render the work 
more acceptable to those for whom it has been prepared. 
EDINBURGH, February 24, 1908, 
