204 
BORING AT SHILL1NGFORD. 
Sep., 1891. 
quartz grains and calcareous matter had been carried down 
from above ; for, on washing it, a residue of large grey quartz 
grains mixed with some fragments of shell was left. Under¬ 
neath this was a compact, grey limestone, 2Jft. thick, and 
apparently the most definite bed of limestone found in the 
whole of the boring. Beneath it were sand and stone, with 
water which was not analysed, but is reported by Messrs. Isler 
to have been fresh and good, not salt. These beds may be 
referred to the lower calcareous grit, with a thickness of 35ft. 
The clay below was soft and clean, and dried to a light 
grey. It was only penetrated to a depth of 4|ft. 
The members of the Corallian group are known to change 
their characters within short distances, and, as they thin out 
altogether to the north-east of Oxford, it is not very surprising 
to find that the Corallian beds at Shillingford are very 
different from those-which occur at the outcrop near Oxford. 
At Iffley and Headington they consist of an upper division of 
shelly limestones (25ft. thick), overlying soft sands, with 
layers and doggers of limestone, these lower sands being from 
40ft. to 60ft. thick, and representing the lower calcareous grit 
of Wilts. At Shillingford the total thickness is much the 
same, but the limestone appears to have become shaly and 
argillaceous, while the underlying sands are largely replaced 
by layers of clay and rock. The change appears to be some¬ 
what similar to that which is known to take place along the 
outcrop to the north-east, and it would thus seem that, in 
passing both to the N.E. and to the S.E. from Oxford, we 
travel away from the line of coral reefs around which the 
calcareous sandstones and shelly limestones of the typical 
Corallian area were accumulated. 
The Salinity of the Water. 
The salinity of the water derived from the Vectian Sands 
is one of the most interesting results of the boring, though it 
was very disappointing to Mr. Field, inasmuch as the water 
was useless for brewing purposes. When the water first rose 
in the bore a sample was sent to Messrs. Gillman and 
Spencer, who made a partial analysis, and reported as 
follows :— 
Hardness before boiling .. 
Chlorine 
Ammonia 
Do. albuminoid 
Nitrogen as Nitrates 
Nitrites 
Amount of chloride of sodium 
8-96 
119-60 
•128 
•0021 
nil. 
nil. 
197’6 grains.* 
* This is probably estimated in grains per 100,000 parts, and if 
so, it represents the quantity of 138 - 3 grains per gallon. 
