179 
spindle formed valley itself well marked off, and amply illus- 
trates its physical geography. [Such a map was exhibited at 
the reading of this paper. ] 
The general trend of the hill slopes is 8.S.E., and the dip 
of the beds which compose the hills is similar in direction, 
though at a greater angle. On this account we rise geologically 
the further we descend the Cotteswolds towards Swindon, suc- 
cessive higher beds outcropping as the lower ones dip under 
the horizon. The main body of the rocks composing these 
rising grounds around the town is Great Oolite, but all the 
hills around are capped by Forest Marble, or by those junction 
beds between these horizons, which present constant difficulties 
to the local student. 
Our evidence of this paramount importance of the Great 
Oolite around is abundant, but I lay exceptional stress on it in 
this part of my argument for a reason which will be presently 
developed. 
The evidence is afforded firstly, by the quarries, and 
secondly, by the well sinkings in the neighbourhood. 
Avoiding for the moment the question of what exactly is 
Great Oolite, and what Forest Marble, we may say generally 
that all the heights around the town are Great Oolite, with 
cappings here and there of true Forest Marble. The various 
quarries have been described and sections given from time to 
time, chiefly by the late Professor Buckman (in an important 
paper to be presently alluded to), and subsequently by Hull, 
Witchell, and myself. 
The evidence afforded by the deep wells in the neighbour- 
hood, so far as I can ascertain, has not been collected or recorded 
in any way. It may prove useful to some future workers at 
Cotteswold Geology to have what is known placed on record. 
I refer solely to wells which undoubtedly cut through the Great 
Oolite and find their water supply in the Fuller’s Earth below, 
and the situation of these wells on the rising grounds around 
the town gives their history an important bearing on the sub- 
ject of the Geology of the town itself. 
