vi PREFACE. 



Age, is for the most part occupied with a somewhat detailed 

 description of the Glacial deposits, and an exposition of the prin- 

 ciples upon which these are interpreted. It gives only a meagre 

 account of the cave- and river-accumulations which have yielded 

 traces of man and the Pleistocene mammals, while the more 

 recent deposits, with the exception of those of Scotland, are 

 passed over with merely a few general remarks. This mode of 

 treatment was necessitated by the object I had in view, which 

 was to point out to English geologists that in their endeavours 

 to arrange chronologically the ossiferous and Palaeolithic accu- 

 mulations sufficient attention had not been paid to the results 

 which had accrued from a study of Glacial and Interglacial 

 formations. And I sought by a rigid analysis of the evidence 

 to show that the Palaeolithic deposits, which had hitherto 

 been classed by them as of Postglacial age, could not possibly 

 belong to so late a period, but ought to be referred to Inter- 

 glacial, and probably in part also to Preglacial, times. The plan 

 of my former work, however, did not allow of so full a treat- 

 ment of this part of the subject as its importance demanded, and 

 the preparation of the present book was forthwith commenced, 

 with the view of supplying such deficiency, and of still further 

 illustrating and substantiating my general argument. 



Many questions, which hardly came within the scope of my 

 previous essay, are here discussed at some length. Chief among 

 these are the physical changes that characterised the Postglacial 

 and Recent Period. Since the appearance of Edward Forbes's 

 well-known paper on the Geological Eelations of the Fauna and 

 Flora of the British Islands, great advances have been made in 

 our knowledge of the later chapters of the geological record ; and 

 I have taken advantage of this fuller information to reconsider 

 some of those questions of geographical and climatic change 

 which the genius of Forbes suggested. The subject is extremely 



