178 
South Cerney. This rock was first called ‘‘ Kellaway’s Stone” 
by Witi1am Suite; and, in his work “Strata Identified by 
Organized Fossils, containing prints on coloured paper of the 
most characteristic specimens in each stratum,” 1816, p. 28; 
he says—“ The excavations of the Kennet and Avon and 
Wilts and Berks canals exposed new outcrops of this stone, 
which I afterwards found on the Thames and Severn Canal, 
near South Cerney.”” No doubt he here refers to the cutting 
which would be made through precisely the same knoll, or spur 
of rising ground, when the canal which cuts through it not far 
from our railway cutting, was made. There is no trace now on 
the banks of the canal of the particular strata, as they have 
long been covered by soil and vegetation; but, from the 
measured levels there can be no doubt that the beds extend 
northwards, beyond the canal. I have evidence of their exten- 
sion southward to the end of the spur. 
The thin shelly band (5) is composed almost entirely of 
Gryphea dilatata, a characteristic Lamellibranch of the Oxford 
Clay. These again crumble on exposure, and good specimens 
are obtained with difficulty. 
The bed of Caleareous Limestone (6) is the particular 
stratum of this section to which the attention of students has 
been specially drawn. The interest of the cutting may be said 
to centre in this one bed. For that reason I may be excused 
for giving a more detailed description of it. In physical 
characters the rock is of a light bluish grey colour, is exceed- 
ingly hard and “obstinate,” blunting the chisel of the 
excavators, and resisting any forces but those generated by 
dynamite or gunpowder. Our colleague, the Rev Dr Smrtue, 
has kindly made a careful microscopical examination of the 
rock, and favours me with this report of it:— 
“The small piece of Kellaway’s Rock was subjected to 
CorpIER’s process, which method answers very well for simple 
rocks (see ZIRKEL, die mikroskop. beschaff. &c., p. 7). The 
result comes out thus :—Quartzose grit, containing grains of 
dirty-coloured quartz, mingled with other grains of hyaline 
pellucid quartz—both of them are crystallised in the usual 
