Sep., 1891. 
BORING AT SHILLINGFORD. 
207 
Many other cases of deep-seated saline waters exist, and it 
is noticeable that they may proceed from clays and limestones 
as well as sands and sandstones, and several explanations of 
the salinity have been suggested. Two of these have been 
recently examined by Mr. H. B. AVoodward in his paper on 
the Swindon boring.* In this boring salt water was met with 
at two horizons, the first supply rising from the Coral Bag, 
below seventy-two feet of Kimeridge Clay ; and the second, 
from the Forest Marble, at a depth of 730 to 736 feet. The 
first contained eighty-six grains of sodium chloride and forty- 
nine grains of sodium carbonate per gallon ; the second 
contained more than 2.000 grains of solid matter in the gallon, 
of which 1,824 grains were sodium chloride. 
Air. AA^oodward discusses the possibility of the salt water 
being derived from the salt-bearing Triassic rocks, but 
dismisses this theory as an unlikely one to account for the 
Swindon case. He points out the frequency of salt waters 
rising from Palaeozoic rocks, and is inclined to believe that 
the Swindon waters rise from a ridge of such rocks at a 
considerable depth, so that the purer water percolating 
through the Jurassic strata is rendered locally saline by 
mixture with that rising from below. As to the means by 
which the uprise of the water is facilitated, he notices the 
possibility of its passing upward through fissures or lines of 
fault, but perceives the difficulty of supposing open fissures to 
traverse such thick and compact masses of argillaceous 
material as the Oxford Clay. He prefers to assume the 
existence of a ridge of Palaeozoic rocks, and to suppose that 
the Secondary strata are banked against this ridge in such a 
manner that water may find its way directly from the former 
to the latter at more than one horizon. 
Apart, however, from the assumptions which he admits to 
be involved in this hypothesis, there is the fact that the 
quality of the saline waters varies greatly within short 
distances, and that in several cases near Swindon good fresh 
water has been found by boring through the Kimeridge Clay 
into the Coral Bag ; whereas, if the saline water finds its way 
horizontally from a subterranean ridge along the permeable 
strata, one would certainly expect all the water derived from 
one stratum in the district to be more or less saline. It is 
still more difficult to apply the hypothesis to all the cases of 
saline waters that are known in the counties of Wilts, Berks, 
and Oxon ; neither can we suppose that in eve^y case such 
* Quart. Journ. Geol. Soc., vol. lxii., p. 289. 
