48 
Fic.1. AVON SECTION : Snowe THE UNnconForniry. 
SSE: 
CLIFTON 
DOWN 
DOWN 
DURDHAM 
PROCEEDINGS COTTESWOLD CLUB I9OI 
TRIAS. 
SS 
PANS 
90S, 
=a) 
UPPER . MILLSTONE COAL 
UPPER 
SHALES LIMESTONE SHALES GRIT 
? 
\ 
UPPE 
“OLD RED 
SANDSTONE 
\ 
MIDDLE UPPER 
LIMESTONE 
LOWER 
LOWER 
MEASURES 
\ 
FAULT 
SHALES 
SHALES LIMESTONE 
‘lands is 4,000 feet. 
Bristol district, the Coal Mea- 
sures are underlain by older 
strata down to a considerable 
depth in the Old Red Sandstone. 
Further north, lower beds of the 
Old Red make their appearance ; 
and at Ledbury the Old Red 
passes down into the Silurian 
series, which shows its basal 
member typically developed at 
May Hill. At the base of the 
Silurian there is a marked uncon- 
formity ; but between the basal 
Silurian and the Coal Measures 
the formations appear to follow 
each other in conformable se- 
quence. Insome parts of Glou- 
cestershire, according to Prof. 
Lloyd Morgan,’ the succession 
is apparently broken, and west 
of Cromhall the Old Red is re- 
duced to a band of but two or 
three hundred feet ; but on the 
other side of the Severn the 
Silurians and the Old Red are 
in full force, and again in Devon- 
shire the latter reaches a thick- 
ness of from 10,000 to 12,000 
feet. The normal thickness of 
the Silurian in the West Mid- 
In the 
Bristol area, the Carboniferous 
Series is estimated at 9,400 feet. 
The aggregate thickness of the 
1 Handbook, Brit, Assoc., Bristol, 1898. pp. 12, 13. 
