GREAT OOLITE: CIRENCESTER. 283 
A well sunk at the Farm was carried to a depth of 140 feet, 
into the Fuller's Earth. The full thickness of the Great Oolite 
probably does not exceed 120 feet. 
The task of fixing a precise division between Great Oolite and 
Forest Marble, is difficult enough in the neighbourhood of Ciren- 
cester. From a general point of view there is indeed a marked 
difference between the white limestones, the marls and more or 
less shelly oolites that belong to the Great Oolite ; and the hard 
oolitic shelly and sandy flags and planking of the Forest Marble, 
separated as these are by beds of clay, and accompanied as they 
sometimes are by sands and concretionary masses of calcareous 
sandstone. Nevertheless the junction-beds not unfrequently 
comprise alternations of marls and clays with shelly and oolitic 
limestones, there being clayey bands, sometimes crowded with 
Ostrea Soicerbyi, at several distinct horizons. The fauna of the 
Bradford Clay is only preserved here and there ; and to the north 
and north-east of Cirencester, as remarked by Prof. J. Buckman,* 
we have but rare indications of it. On the whole the flaggy beds 
of Great Oolite are not so hard nor so thinly divided, as are those 
of the Forest Marble ; nor when obliquely bedded, are they sepa- 
rated by the even bands of blue and shaly clays that mark the 
Forest Marble. Again, the Forest Marble limestones are usually 
characterized by ochreous clay-galls, and they are more often blue 
in colour, owing to the protecting layers of clay associated with 
them. 
Great Oolite has been quarried in several places bordering the 
Great Western (branch) railway south of Cirencester station. 
The junction-beds with the Forest Marble are shown in some of 
the openings, and it is evident that the clays and marl-beds are 
of varied thickness in different places, and it is impossible to 
correlate the layers, bed for bed, in the several exposures. 
The following section was shown in one of the quarries : 
FT. IN. 
f Clay, with band of blue flaggy oolitic 
tf 4- -M 1 i J anc ^ shelly limestone - - - 2 6 
)le '| Brown and bluish clay, with band of 
I marly oolitic limestone - 3 6 
f Hard blue and brown oolitic and shelly 
p , , limestone - - - - 3 
>as - 1 Oolitic marly clay, with " race," and 
I Ostrea - - - - - 1 2 
f Pale oolite, (with Ostrea) - 4 6 
Great Oolite -| Marly clay, with Ostrea - - 6 
I Pale false-bedded oolites - - 17 
Echinobrissus Griesbachi was obtained from the Great Oolite 
at this locality. Other Echinoderms also occur sometimes abun- 
dantly in this neighbourhood. A large nrmber of specimens 
(many hundreds indeed) of Acrosaltnia pustulata, were obtained at 
Cirencester, by Fred. Bravender and T. C. Brown, in the winter 
1858-59. f The following section was given by Bravender: 
* Quart. Journ. Gcol. Soc., vol. xiv. p. 1J7. 
f Wright, Ool. Echin. Pal. Soc., pp. 460, 461. 
