6 
LOWER OOLITIC ROCKS OF ENGLAND: 
The following Table shows the varying nature of the supposed 
Tripartite series : 
Formations. 
Leading Lithological 
Characters. 
Grouping of 
John Phillips.* 
Grouping of 
Conybeare and 
W. Phillips.f 
Purbeck Beds 
Limestones and clays. 
Portland Beds 
J Limestone - 
\ Sand 
Calcareous 
Arenaceous 
Limestone. ~| 
Sand. > 
Kimeridge Clay 
Clay 
Argillaceous 
Clay. J 
Corallian Beds 
f Limestone - 
\ Sand 
Calcareous - 
Arenaceous 
Limestone. 1 
Sand. \ 
Oxford Clay - 
Clay 
Argillaceous 
Clay. J 
Kellaways Eock 
Sand. 
Cornbrash 
Limestone - 
Calcareous 
1" Clay and sand 
Arenaceous - 
Forest Marble 
< Limestone - -"I 
[Clay - -J 
Argillaceous - 
Great Oolite - 
Stonesfield Slate 
Limestone - 
Sand and limestone - 
Calcareous 
Arenaceous 
Limestone. ~) 
[Clay - --) 
Fuller's Earth 
1 Limestone - } 
Argillaceous - 
I Clay - -J 
Inferior Oolite 
Limestone - 
Calcareous 
Midford Sand 
Sand 
Arenaceous 
Sand. 
Upper Lias - 
Clay 
Argillaceous -") 
1" Limestone. 
Middle Lias - 
\ Sand. 
I Clay. 
Clay. 
f Clay 
Lower Lias 
I ^Jiaj . 
\ Limestone. 
J 
[ Limestone. 
Khanic Beds - 
1 Clay. 
It will thus be seen that the so-called " tripartite series" is by 
no means constant, and that the exceptions are almost as frequent 
as the rule. Especially is this the case when we come to trace 
the divisions from the south of England through the Midland 
counties into Yorkshire. Nevertheless considering the matter in 
its local aspects it is deserving of some attention. As a rule we 
are taught that the sands were formed near shore, the clays 
further off, and the limestones in the deeper water. In the case 
of the oolites, however, the evidence tends to show that most if 
not all of them must have been accumulated as shore-formations 
in shalloAv water ;J and it is desirable to consider their origin before 
proceeding further. 
Oolitic Rocks. 
The term oolite in a petrographical sense is usually restricted 
to rocks that contain small roe-like grains having a concentric 
and radiate, or simpl) a concentric or radiate structure, formed 
* Geol. Oxford, p. 393. 
f Outlines of Geol. England and Wales, pp. 165-167. 
$ See also Duncan, Quart. Journ. Geol. Soc., vol. xxxix. p. 196. 
