Reviews — Shore Processes and Shoreline Development. 563 



subject. In every direction there is room for the development of 

 fresh lines of investigation, as well as for renewed activity along 

 paths already trodden. Whether my particular suggestions prove 

 fruitful or not, they will have served their purpose if they have 

 stimulated anyone to look for new fields of work. 



Postscript. — Since this address was written, I have learnt that 

 Professor Kendall has from time to time made valuable suggestions 

 with regard to the association of the Survey with local workers, 

 more especially the geological staff and students of our colleges. 



IRE^T-HE^TS. 



I. — Shore Processes and Shoreline Development. By Douglas 

 Wilson Johnson. 8vo ; pp. xvii + 584, with 73 plates and 149 

 text-figures. New York, John Wiley & Sons, Inc. ; London, 

 Chapman & Hall, Ltd., 1919. Price 23s. net. 



WHILE this book was in preparation Mr. Johnson was Associate 

 Professor of Physiography in Columbia University. When he 

 wrote the preface he was on his way to France, and he claims the 

 indulgence of the reader for the lack of the final supervision which he 

 had hoped to give the proofs. But it is only in details that 

 indulgence is needed; in essentials the book seems to have suffered 

 little from the circumstances under which it was produced. 



It is the best and most complete exposition of its subject that 

 has yet appeared. The style is lucid, though at times unnecessarily 

 diffuse; the work of previous writers is discussed, with copious 

 references to the original papers, but the author retains his own 

 independent judgment, which is always thoughtful and never 

 dogmatic. Even where the reader disagrees he will recognize that 

 the author is making an honest attempt to discover the truth and is 

 not endeavouring to enforce a preconceived opinion. 



The general scheme of the work is clear and logical. The first 

 three chapters deal with waves and currents, these being the chief 

 agents, apart from changes of level, that tend to alter the shape and 

 character of coasts. Questions of terminology and classification are 

 next discussed, and having thus cleared the ground the author 

 proceeds to consider the development of the shore, a subject which 

 occupies nearly half the volume. In his treatment he separates the 

 " shore profile ", or the shape of the shore in section, from the 

 " shoreline ", the shape of its outer boundary in plan. Finally, 

 there are two chapters on special features, such as beach ridges, 

 ripple-marks, etc. 



In the chapters on waves no attempt is made at a mathematical 

 analysis of wave-motion, which would indeed be out of place in 

 a work of this nature ; but there is a summary of the results 

 obtained by such analysis. On the vexed question of the depth at 

 which wave-action is perceptible the author adopts the widely held 

 opinion that 600 feet may be taken as the limit for ordinary wave- 

 disturbances, though occasionally effective motion may descend beyond 

 that depth. 



