THE LAST DECADE, 
419 
At a meeting held at Hull in April, 1881, Mr. A. G. Cameron, 
of H.M. Geological Survey, drew attention to subsidences over the 
Permian boundary between Hartlepool and Ripon. The phenomena 
are similar to those described by the Rev. J. Stanley Tute, in a 
previous communication to this Society. A number of instances are 
cited of pits which occur northwards from Ripon. The initiative to a 
number of the pits may have been given by the river at a time when 
confined between high and overhanging crags, as it must once have 
been about Ripon. It beat ceaselessly against the walls of the 
narrow gorge which would become caverned and rugged by the force 
of the torrent. On the boundary walls of this ravine the subsidences 
took place more frequently than elsewhere, and this may be due to 
the strata being in greater dilapidation from the above causes, areas 
less compact than tliis determining the locality of the pits. A more 
probable explanation is that where the underground water, flowing 
over the limestone surface, reaches the margin of the sandstone it 
receives a check whereby it accumulates, forming a chain of dams or 
pools along the line of junction of these rocks, as denudation pro- 
ceeds hollows will form above and below until ultimately the pheno- 
mena of the pits appear. In the neighbourhood of Hartlepool the 
Permian and Triassic rocks dip or roll towards each other indicating 
a trough extending longitudinally in the direction of their boun- 
dary. There are thick beds of salt only a very short way from 
Hartlepool, and it is possible that when the coast line extended 
further into the present bay the drainage off the land may have 
found access to beds of salt below, and dissolving them caused a 
cavity into which the overlying strata has sunk, giving rise to the 
large pool called the Slake. Other instances in neighbouring forma- 
tions are given and compared with those of the Permian. Bearing 
on a similar subject, Mr, T. Fairley contributed a paper on the blow- 
ing wells near Northallerton. Three of these wells occur at Salberg, 
Langton, aud Ornhams. In each of them currents of air flow from 
the shafts of the wells during a falling period of the barometer, and 
inward currents flow into the shafts of the wells while the barometer 
is rising. When the rise or fall of the barometer is considerable, the 
currents are very powerful, producing a strong draught or wind in 
