Sep., 1891. 
BORING AT SHILLINGFORD. 
203 
The presence and thickness of the Vectian (Lower Green¬ 
sand) are important as showing that it may be expected to 
extend still farther eastward, and nossiblv to come within the 
limits of the London basin. In this connection it is a matter 
of regret that the Bushey boring was not carried through the 
Gault with the object of ascertaining the nature of the under¬ 
lying strata at that spot. The Vectian sands yielded a 
copious supply of water at Shillmgford, but on analysis it 
was found to contain a certain amount of free ammonia, and 
a large amount of sodium chloride. 
The Kimeridge Olay appears to be 111ft. 6ins. 
thick, a depth which very nearly agrees with Professor 
Phillips’s estimate of its thickness near Shotover. It had the 
usual character of a dark-coloured clav, with numerous 
remains of crushed shells, and contained a layer of phosphatic 
nodules near the base, among which casts of a Trigonia 
occurred. 
At a depth of 299|-ft. a hard rock was reached, but I did 
not succeed in obtaining a satisfactory specimen, a small piece 
shown me as coming from this horizon was a coarse, gritty 
sandstone, and Mr. Field in a letter to me says, “specimens 
from 314 to 318ft. included small pieces of hard, grey, gritty 
stone and hard, yellow loam which was soft at first but 
hardened on drying into a fine, gritty stone.” We may con¬ 
clude that this part of the section consisted of loamy clays and 
marls with layers of hard grit and sandstone. A specimen 
from 318ft. contained broken bits of grey limestone. 
These beds were succeeded by argillaceous strata with 
layers of “ rock,” but all more or less hard, so that the punch 
was used continuously, and no good samples were obtainable. 
Fragments of oyster shells were abundant throughout. 
I was at first inclined to class these beds down to a depth 
of 344ft. 4ins. with the Kimeridge Clay, as they did not appear 
to contain thick beds of limestone such as generally occur in 
the Corallian group ; but, having regard to the great change 
which takes place in the composition of this group north-east 
of Oxford, I now think a somewhat similar change may take 
place to the south-east, and that these marly, gritty, and 
shelly beds may really represent the limestones of the Coral 
Piag. 
Below this the record is sand and stone, and then alterna¬ 
tions of hard grey rock with tough clays, which were 
described as similar to those between 318ft. and 335ft., the 
whole requiring to be punched. Next came 10ft. of softer 
material, a specimen of which from 370ft. was a dark, cal¬ 
careous, gritty clay, probably a nearly black clay into which 
