PREFACE. 
The excellent series of photographs, which form the most 
attractive feature of this paper, were all taken by Prof. S. H. 
Reynolds, M.A., F.G.S., who has devoted much time and trouble 
to the satisfactory illustration of the Avon Sequence. 
The cost of publication of the plates has been most generously 
defrayed by a large number of geologist-friends. 
To them, and to Prof. Reynolds, are due the thanks, not only 
of myself, but of all those who are interested in the study of 
the Carboniferous Limestone. 
In the hope of making the text worthy of the illustrations, 
of the kindness of the contributors, and of the grand section 
with which it deals, I have carefully revised my earlier work 
and have included the results of later research. 
A. V, 
Clifton, May , 1906. 
73 
G 
