184 PROCEEDINGS OF THE GEOLOGICAL society. [Dec. 15, 
it is chiefly the lower 30 or 40 feet of the great oolite which will en- 
gage our attention, inasmuch as the testacea of the other divisions 
are unimportant with respect to number of species, and rarely contain 
any which are not likewise found in the testaceous portion referred to. 
The general geological features cf the neighbourhood are already 
sufficiently known ; all the exposed sections are artificial, the quar- 
ries are openwork, and nearly the whole are situated in the parishes 
of Minchinhampton and Bisley, near escarpments of the oolite, 
caused by the two deep valleys of Chalford and Woodchester, with 
their lateral ramifications. These valleys of denudation have cut 
through the series of rocks from the forest marble to the has, having 
a mean depth of 500 feet, and have produced a combination of cir- 
cumstances eminently favourable for bringing the valuable beds of 
oolite into use at a small comparative expense, and of transporting 
it by water-carriage. 
The rocks have the same general dip to the south-east, at a small 
angle, which usually prevails over this part of England. Many sec- 
tions indeed exhibit a dip at variance with this general position, 
and one lateral valley (Toadsmere) has an anticlinal axis producmg 
considerabie upthrow of the beds on each side. These variations 
however from the general rule are local only, and do not affect the 
inclination cf the beds when viewed on a large scale. 
Joints (lissens of the quarrymen) are for the most part parallel mn 
their direction and frequently widely separated. In one curious 
instance a large Nautilus was severed by a joint, and the divided 
portions remained a yard apart on opposite sides of the chasm. Our 
sections, though numerous, are but of small extent, and have not 
disclosed any fault or displacement of importance, nor is there any 
reason to suspect the occurrence of such within the limits here chosen. 
The compound great oolite, irrespective of the Fuller’s earth, has 
an aggregate thickness of about 130 feet, and will admit of the fol- 
lowing general subdivisions :— 
1. Forest marble beds with bands of clay and mar! representing the 
Bradford clay. 
2. Thin-bedded sandstones, not shelly. 
3. Weatherstone, being the portion quarried for building purposes. 
This subdivision is distinguished from the one above by the 
superior thickness of the beds, their shelly structure and fre- 
quent diagonal lamination, thereby approaching in general aspeet 
the uppermost or forest marble beds. The two former sub- 
divisions occupy the surface to the east of the town of Min- 
chinhampton ; the latter is exposed to the west and north. 
The forest marble series consists of many very irregular thin beds 
of oolitic sandstone more or less shelly, and frequently separated by 
bands of brown or grey marl or clay; these latter are the probable 
representatives of the Bradford clay; the Terebratula digona how- 
ever does not occur in them, although they contain many bivalves, 
the most conspicuous of which is the Cardium Beaumonti, d Archiac. 
Some of the shelly beds are very hard, split to thin lamine, and 
