DECEMBER 6, 1906 | 
NATURE 
A GEOLOGICAL HISTORY OF DEVONSHIRE. 
HE title of this book requires some explanation, 
for the subject-matter is not a description of the | 
existing scenery of Devon, or of the manner in which | 
its various features have been developed out of the | 
rock-surfaces which last rose above the sea. It is | 
mainly a description of the physical and geographical | 
conditions under which the rocks of the south-west 
of England were formed; it is an endeavour (as in- | 
dicated by the subtitle) to follow the geographical | 
evolution of the region, and to picture the successive | 
stages in the development of its physical geography. | 
The aim of the author has evidently been to present | 
what is known of the geological history of Devonshire | 
in as interesting a form as possible; hence, as stated 
in the preface, he has used ‘‘ the minimum of tech- | 
Devon begins to be readable from its own records,”’ 
this, of course, being the Devonian period. Having 
first indicated the probable geography of Britain at 
this time, the author describes the rocks of North 
Devon, indicating the great compression and contor- 
tion to which they have been subjected. He mentions 
the diverse views which have been held regarding 
their succession, and wisely remarks that further 
investigation is required before this matter can be 
settled. 
The next chapter is devoted to the Devonian of 
South Devon, of which a good description is given, 
with a glance at the schistose area of the Start, laying 
stress on the fact that the results of compression and 
metamorphism become greater in the direction of 
these crystalline rocks. It was perhaps to be ex- 
pected that he would repeat the statement that the 
Fic. 1.—Vhe Haven Cliff, Axmouth. 
nical language with the object of making them (his 
pages) suitable for the beginner and the ordinary 
reader who has no previous knowledge of the subject, 
but who cares to know how Devonshire came to be 
what it is.” 
Moreover, he has contrived to include much general 
information regarding the rocks of the British Is- 
lands, and since many modern geologists consider 
that professorial teachers of geology have dwelt too 
much on the lithological and structural branches of 
the science, and too little on its connections with 
physical geography, such a book as this ought to find 
a welcome in many quarters. : 
After an introductory chapter devoted to ‘‘ Proto- 
zoic’’ tims, ‘‘ we reach the date when the history of 
1 “The History of Devonshire Scenery—An Essay in Geograph’‘cal 
Evolution.” By A. W.Clayden. Pp. 2023 with 41 photographic il.ustra- 
tions and some diagrams. (Exeter: J. G.Commin; |.ondon: Chatto and 
Windus, 1906.) Price ros. 6d. net. 
NO. 1936, VOL. 75] 
ra 
/ 
Greensand on eroded surface of Keuper Marls. 
From ‘‘The History of Devonshire Scenery ” 
Devonian limestones are essentially of coralline origin, 
and are to be regarded as ancient coral-reefs, for he 
could quote a recent Geological Survey memoir to that 
effect. Nevertheless, its truth has more recently been 
questioned, and it has been shown that large parts 
of the limestone are crinoidal, while others are chiefly 
made up of Stromatoporoids; moreover, we do not 
know whether any Palwozoic corals were reef- 
builders. 
In chapter vi. we find a general account of the 
Carboniferous rocks before coming to those of Devon, 
the description of which is not very satisfactory, be- 
cause it is entirely based on the old view that the 
Coddon Hill cherts overlie the limestones, and that 
the whole group represents the lowest part of the 
Carboniferous Limestone of Bristol and South Wales; 
whereas good reasons were given by Dr. W. Hind in 
1904 for placing the cherts below the limestones, and 
for regarding both as the equivalents of the Pendleside 
