PREFACE. 
The present work, forming the fourth volume of the Mono- 
graph on the Jurassic Rocks of Britain, contains an account by 
Mr. H. B. Woodward of the Lower Oolitic Rocks of England 
lying to the south of the Yorkshire district already described in 
the first volume. 
The same general plan of treatment has been continued as was 
adopted in describing the Lias. Each sub-division of the Lower 
Oolitic series is first sketched in regard to its leading stratigraphies! 
and palaeontological characters, and then local details are given 
to illustrate the variations which the strata present as they are 
followed along the strike across the country. A general 
description follows of the influence of the Lower Oolitic rocks upon 
the scenery and the soils of the districts where they occur; their 
economic products are then enumerated, and an account is added of 
their relation to the question of water-supply. 
In the Preface to Volume III. attention was called to various 
early geological maps of the Jurassic areas of England, and likewise 
to the maps of the Geological Survey. In regard to the Memoirs 
of the Survey much assistance has been derived from them by 
Mr. Woodward in the preparation of the present volume, 
especially from those dealing with the Lower Oolitic rocks, by 
Prof. Hull, Prof. Green, Prof. Judd, Mr. Ussher, and Mr. Jukes- 
Browne. 
Besides the large number of stratigraphical sub-divisions 
generally recognised in the series of formations described in the 
following chapters, many more have been based by palaeontological 
writers upon the local horizons of species. The number and real 
value of such palseontological zones and horizons must obviously 
depend a good deal upon individual views concerning species. 
In adopting broad palaeontological sub-divisions rather than 
minutely defined and often merely local zone?, Mr. Woodward has 
been guided by the evidence he has been able himself to gather 
from a careful study of the sections in the field, together with the aid 
supplied by the palaeontological determinations made for him by his 
colleagues, Messrs. G. Sharman and E. T. Newton. In this general 
Memoir, which is intended to present a broad but detailed picture 
of the subject of which it treats, it would obviously be impossible to 
enter into such minute particulars as are mainly of local interest, 
or belong rather to the domain of the specialist in some restricted 
field of palaeontological research. 
The literature of the subject, probably more extensive than that 
of the Lias, has so far as is possible been attentively studied. It is 
intended that a full bibliography shall appear in the next volume 
which, treating of the Middle and Upper Oolites, will conclude the 
account of the Jurassic rocks of England and Wales. 
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