THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
147 
Mr. Bailey Denton , some years ago, secured the drainage 
of several hundred acres, on Lord Dillon’s estate, in Oxford¬ 
shire, by bringing the water to a shaft, three feet in diameter, 
sunk for twenty to thirty feet in the Oolite, and disposed 
of the whole of the water. 
Mr. W. H. Wheeler, Mem. Inst. C. E., says* that in the 
Oolitic limestone districts, the waters from ditches may be 
frequently seen, when running a full stream from eighteen 
inches to two feet deep, to disappear from the surface, and be 
absorbed by swallow holes. 
Professor Judd, F.R.S., saysf that “in the district 
embraced by sheet 64 of the one-inch Geological Survey 
Maps, ‘Swallow Holes’ are very common, the lines of 
junction of rocks, like the Upper Estuarine Clays and the 
Lincolnshire Oolite, are often marked by a series of these 
natural drains, a slight depression in the surface often 
indicating their position. In some cases the volume of water 
carried off by means of them is very great, and the roar 
produced by it in descending is heard at some distance. 
Smaller swallow holes may often be detected by placing the 
ear near the surface of the ground.” Professor Judd further 
says:—“ These swallow holes are well known to fox hunters, 
for the long sinuous fissures worn by the constant passage of 
water through the jointed limestone rocks constitute retreats 
for foxes, from which it is almost impossible to effect their 
dislodgment. Doubtless, also the caverns so frequently 
revealed in the midst of limestone rocks, during quarrying 
operations, owe their formation to the same agency. In 
effecting drainage operations, these natural means of carrying 
off the surface water are often imitated, and artificial 
swallow holes constructed, and they effect the removal of 
the largest volumes of surface water.” Professor Judd gives two 
or three instances of a whole river disappearing into a porous 
bed, and re-appearing at the junction with the next impervious 
one, after flowing for a considerable distance, sometimes 
several miles : The River Witham, near Thistleton; the River 
Glen, between Little Bytham and Careby; and the brook 
which flows by the village of Benefield. Natural swallow 
holes will only be of common occurrence where the alternating 
* “Arterial Drainage and the Storage of Water,” by W. II. 
Wheeler, M.I.C.E., Journal of Royal Agricultural Society, vol. xxvii., 
part 1. 1878. 
t “ The Geology of Rutland, and the parts of Lincoln, Leicester, 
Northampton, Huntingdon, and Cambridge, included on sheet 64,” 
by Jno. W. Judd, F.G.S. Memoirs of Geological Survey. 
