IV 
Mr. Keid hns been able to enter more fully into such questions as 
the physical conditions under which the Pliocene strata were 
deposited, the climate and the natural history of the seas of 
later Tertiary time, the terrestrial movements of Pliocene date and 
their relation to the topography of the south of England and to 
the existing physical geography of north-western Europe. 
In any work treating of the Pliocene deposits of Britain a fore¬ 
most place of recognition must be given to the names of Charles- 
worth, who proposed the divisions now adopted; Lyell, who 
classified the whole Tertiary series; Prestwich, who did such 
eminent service in the Crag district and at Lenham; S, Y. Wood, 
whose Crag Mollusca” is one of the classics of Geology; and 
Messrs. Wood, Junior, and Harmer, who made the first detailed 
map of the Pliocene deposits of the eastern counties. Of the 
labours of these and other observers large use has been made in 
the following chapters, as the references in the text will show. 
I have to express my thanks to Professor Prestwich and to the 
Council of the Geological Society for permission to use the wood- 
cuts from the Quarterly JournaP’ of that Society; also to many 
foreign geologists for the assistance they have so freely rendered 
to Mr. Reid in his researches, especially to M. E. Van den Broeck, 
and to M. Cogels, and Baron Van Ertborn in Belgium; to 
Professor De Stefani, Dr. Ristori, Dr. Canavari, Professor 
Capellini, Professor Meli, Professor Sacco, and the late Professor 
Meneghini in Italy ; to M. G. Dolfuss and M. Maurice Vignier in 
France ; and to Dr. J. Lorie of Utrecht. Many of these geologists, 
besides communicating valuable information or facilitating a study 
of the specimens in the museums under their charge, accon;ipanied 
Mr. Reid into the field and thus enabled him to obtain full and 
accurate information regarding the sections which he visited. 
ARCH. GEIKIE, 
Director-General. 
Geological Survey Office, 
28, Jermyn Street, London. 
4th June 1890. 
