GREAT OOLITE: DAGHAM STONE. 287 
Lycett attributed these irregular holes " to the forcible escape 
of gases from beneath while the stratum was of a soft or pasty 
consistence " ;* and Prof. Allen Barker considers them to be due 
to the action of humic acid.f Witchell, again, remarked that 
these beds full of holes, have been called " holy-stones," and that 
" the probable explanation of this peculiarity is that the calcareous 
matter was deposited round soft substances which have been 
dissolved or otherwise removed, and through the labours of boring 
animals when the surface of the limestone was the floor of the sea/'J 
The rock itself is a pale slightly oolitic limestone, that occurs 
in the White Limestone division of the Great Oolite. It is not, 
however, confined to one particular horizon, as two or more layers 
exhibiting these cavities may sometimes be observed, separated 
by some thickness of other beds. Where seen at some depth 
beneath the surface the cavities are filled, or partially filled, with 
ochreous marl containing oolitic grains ; and although occasionally 
small cavities may be due to the decomposition of branching 
Corals, as I take to be the case at Minchinhampton, or of 
clusters of oolite grains that occur in the compact limestones, yet 
in the majority of instances no definite structure can be found 
associated with them. 
Stone showing these curious hollows has been found in many 
places near Cirencester ; but in most cases the stone has not been 
subjected to surface weathering, as on Dagham Downs. Lycett 
mentions the old monumental stone, the Longstone, near Minchin- 
hampton, as being formed of rock full of irregular holes. 
In a quarry in white and slightly oolitic limestone at Eastcombs 
near Bisley, the stone contained these ramifying ochreous perfora- 
tions, which appeared like ferruginous stainings, to a depth of 
3 or 4 feet, or more. Again near Ledgemore Bottom, north of 
Tetbury the rock is found in a weathered condition. 
The appearances are not confined to the Great Oolite, as I 
have noticed them, on a smaller scale, in the Inferior Oolite 
between Stroud and Painswick. From their position they cannot 
have originated from modern surface-agencies, although these 
have modified and enlarged the hollows, especially at or near the 
surface. In all cases the original structure of the rock must have 
led to the formation of the features ; but even underground the 
ochreous nature of the branching materials, and the sharp and 
irregular outlines of the walls of rock, show that the influence of 
permeating waters has been at work. 
The moat reasonable explanation seems to be that the soft 
calcareous mud was penetrated by burrowing organisms, which 
have left no other traces of their former presence in the now 
indurated deposit, than the irregular lines of weakness caused by 
their burrows. These have been subsequently acted upon both 
superficially and underground, by acidulated waters. 
* Quart. Journ. Geol. Soc., vol. iv. p. 185. 
t Proc. Cotteswold Club, vol. ix. p. 316. See also Phillips, Geol. Oxford, &c., 
p. 243. 
J Geology of Stroud, p. 78. 
