GEOLOGY 
known as ‘crowgold,’ but is nowhere present in the county in suffi- 
cient quantity to be of commercial value. The stratum plays an impor- 
tant part in connection with the water-supply of the district. The 
argillaceous character of the middle portion renders it partially impervious 
to water, so that at its junction with the overlying porous portion 
numerous springs arise, which however are now fewer in number and 
smaller in volume than they were some twenty years ago. This feature 
was strikingly exemplified during the excavation of the extensive cutting 
at Chalton, the flow of water in the Chalk Marl being so copious that 
in driving a heading into the escarpment the workmen had to wear 
miners’ costume, as their clothing was in a state of constant saturation. 
The Chalton cutting is the only exposure of the bed of any importance 
in the county. A sandy layer near its base is not exposed here. 
The ToTTERNHOE Stone takes its name from the village of Tottern- 
hoe about three miles west of Dunstable, where it attains its maximum 
development which does not exceed 22 feet. Away from this locality 
it rapidly diminishes in thickness. It is a dark grey, slightly arenaceous, 
compact limestone, with a peculiar grain to which the term ‘curly’ is 
applied by the quarrymen. The comparative coarseness of the materials 
of which it is composed, and the presence of siliceous particles, indicate 
that there was a temporary increase in the force of the currents which 
effected its deposition, over those which prevailed during the era of the 
Chalk Marl. Scattered irregularly through it are numerous dark brown 
amorphous masses, and at its base there is usually a layer of green-coated 
phosphatic nodules ; a further indication of current-action. Many springs 
arise from it at the foot of the Dunstable Downs and elsewhere. 
Totternhoe Stone was formerly extensively employed in local archi- 
tecture, numerous churches in the south of the county affording 
examples of its use, but it is not sufficiently indurated to withstand for 
any great length of time the climatic changes to which it is subjected 
when used for exterior decoration. It weathers badly, as may be seen 
from the present condition of the west front of Dunstable Priory 
Church.” It is much more suitable for interior work ; but even for this 
it has long been superseded by more durable materials brought from a 
distance. The numerous and extensive relics of excavations on Tottern- 
hoe Hill show that this stone has been quarried for a very long period. 
Until about the middle of the nineteenth century it was customary to 
construct tunnels which commenced at the outcrop of the stone and were 
carried a considerable distance into the hillside. In later times tramways 
were used to bring the material to the surface, the incline, correspond- 
ing with the dip of the bed, being only slight. This system was then 
superseded by open quarrying, the whole of the overlying bed of Lower 
Chalk being removed and used for making lime. This method of 
working terminated during the last decade of the nineteenth century, 
consequent upon the cessation of the demand for the material. 
1 This is now undergoing restoration, the material employed being a Bath stone. 
I 17 3 
