130 L. Richardson—On “ Lissons ”, 
east of Jawalamukhi, where the so-called “ black salt” is won at 
Gama and Drang near Mandi (cf. Medlicott, Mem. Geol. Surv. India, 
vol. iii, p. 60). 
Gas and salt water probably have found their way from depth 
on transverse fractures, and small transverse faults can be proved 
here and there (Fig. 14). 
** Lissons.” 
By L. RicHarpDson. 
ie the Oolitic rocks of the Cotteswold Hills fissures are of frequent 
occurrence. Noticeable phenomena are that when snow or 
hoar frost is on the ground it is usually melted or not deposited along 
the lines of these fissures and that air is usually continuously expelled 
from them. 
In the neighbourhood of Stroud these fissures through which air 
is expelled are known as “ Lissons”’. Air is also expelled from other 
openings in the Oolites—for example, from deep welis. Mr. Charles 
Upton informs me that from a well 175 feet deep down to the water, 
at Bownham Cottage on Rodborough Hill, Stroud, the air was always 
blowing strongly both winter and summer—so strongly, indeed, 
that a lighted candle was immediately extinguished. People who 
live on the Cotteswolds are frequently heard to remark that their 
house is built on “ hot rock”’, meaning thereby that there is a 
‘* lisson ”’ or fissure under the house. The effect of this on the house 
is that it is always damp, and the floors rot and decay in a 
comparatively short time. There are many houses so situated in 
Rodborough. 
In Mr. Upton’s opinion the fissures act as vents for the air which is 
pressed by barometric pressure into the ground over its whole surface, 
more readily, obviously, where the rocks are of a more or less porous 
character, as in the case of the Oolites. The pressure is, of course, 
continuous, and so also is the outflow, but its effects are only visible 
in the winter time, when, as remarked above, the snow or hoar 
frost is either melted or not deposited at all along their line. 
The effects of the pressure of a strong wind is often noticeable 
in wells in the hills. Thus I have been informed that the water in 
the well that supplies Coates, near Cirencester, usually stands at a 
higher level when a strong wind is blowing. 
