LOWER LIAS t RADSTOCK, 127 
may be concluded that the mass of the blue clay here belongs to 
the Middle Lias, and part perhaps to the Upper Lias. 
The Lower Lias in the neighbourhood of Radstock presents 
many remarkable features, to which attention was first called by 
Charles Moore. The beds exhibit in places a considerable attenua- 
tion, while at the same time they are rich in fossils : in this respect 
resembling the Inferior Oolite of Dorset, where a similar diminu- 
tion in the thickness of the strata is attended by a great 
abundance of organic remains. 
The sections near Radstock, moreover, exhibit much variation 
in detail; phosphatized fossils occur at different horizons, and 
there is evidence of the reconstruction of some layers and the 
consequent derivation of some of the fossils from earlier stages, so 
that there is a commingling of species that elsewhere occur in 
more or less distinct zones. At the game time, the general 
succession of the zones of life is not disturbed, although the 
distinctions cannot be always recognized. That there was a 
paucity, and even absence of sediment, over certain areas may be 
safely assumed from the features presented by the different 
sections. Tawney observed that " there really was not sufficient 
sediment to be the burial ground of distinct zones of life."* The 
zones overlap one another and vary much in their distribution : 
for instance, the Spirifer-bed sometimes rests directly on the 
White Lias, and at others it is separated by some thickness of 
limestone. 
As a rule the lowest beds of the Lower Lias consist of two or 
three beds of brown gritty limestone, with ferruginous specks ; 
these are from 18 inches to 4 feet thick, they are fossiliferous, and 
they give rise to a red soil. The beds are known to the quarry- 
men as " Corn grit,"f Higher up there are beds of pale buff or 
yellowish iron-shot limestone that it is not always easy to distinguish 
from the Marlstone or Inferior Oolite.:}: This iron-shot character 
is especially marked in the layers yielding Ammonites Jamesoni, 
and as remarked by Tawney, the little grains of yellow ochre 
produce an oolitic appearance. A section of this iron-shot rock 
from Paulton shows no true oolitic structure ; the specimen was 
sent to Mr. A. Strahan and examined by Dr. Hinde, who found 
that the grains were mostly fragments of Echinoderms. 
The identification of the several zones depends entirely on the 
collection of fossils in situ from each individual layer, and as the 
bands of limestone are often very tough, much labour and patience 
are needed, for the specimens put aside by the quarrymen cannot 
be depended upon for this purpose. Representatives of all the 
zones of the Lower Lias have locally been noticed. 
Spiriferina Walcotti, which locally is a very abundant fossil, 
occurs chiefly in a clay-band, belonging to the zone of 
A, Bucklandi. Many of the Brachiopoda recorded, are those 
* Tawney, Proc. Bristol Nat. Soc., ser. 2, vol. i., pp. 172-175. 
f Lonsdale, Trans. Geol. Soc., ser. 2, vol. iii. p. 246. 
j See also Eucklaud arid Conybeare, Trans. Geol. Soc., ser. 2, vol. i. p. 300. 
