VI STRATIGKAPHICAL GEOLOGY 



information I am supported by many teachers of geology, who 

 wish their students to take a broader view and to learn 

 more about the geology of Europe, with perhaps less local 

 detail of English subdivisions and zones. In order to show 

 how such wider knowledge can be utilised and made interest- 

 ing, I have appended to each chapter a brief sketch of the 

 conclusions which may be drawn from the facts with regard 

 to the physical and geographical conditions under which 

 each great series of strata was accumulated in the European 

 region. 



Further, in three cases I have ventured to express these 

 conclusions in the form of cartographical restorations, i.e. of 

 the Lower Devonian, the Upper Trias, and the Lower 

 Cretaceous. Such maps form a conspicuous feature in the 

 later editions of de Lapparent's treatise, but have not yet 

 been inserted in an English text-book. In a future edition I 

 may be able to include maps of other epochs ; meantime, I 

 would suggest that students should endeavour to make their 

 own geographical restorations from the descriptions which I 

 have given. I need hardly seek to justify such advice, for, 

 as Professor Watts has remarked, such maps " group together 

 numbers of facts and inferences with which it was previously 

 difficult to retain touch ; " . . . they " systematise future 

 research, they direct to the places where the discovery of 

 new facts is desirable." 



In the work of revision I have sought the assistance of 

 those geologists who have paid special attention to particular 

 formations. Their writings are, of course, referred to in the 

 text, but I have to thank the following friends and corre- 

 spondents for reading portions of certain chapters, and for 

 useful information thereon : C. T. Clough, Edward Greenly, 

 W. G. Fearnsides, J. E. Marr, A. Vaughan, E. A. Newell 



