VAUGHAN : THE KXOLL REGION OF CLITHEROE, ETC. 
43 
Shales-with-Limestone, aithoiigli he seems often to imply it ; recent 
work points to a considerable interval between the highest of the 
Clitheroe knolls and the shales which succeed it). 
(2) Correlation with the Avonicm Zones. 
BOWLAND SHALES. 
Although these shales form a continuous and striking lithological 
feature throughout the knoll region, the basal beds are not of precisely 
the same age at all points of the region : — 
On Pendle Hill, they contain Glyphioceros bilingue and are the 
true base of the Millstone Grit (and therefore j^ost Pendleside " of 
Hind and Howe). 
In S. Craven (Thorpe, Cracoe, etc. near Grassington) the basal beds 
of the shales which wrap round the knolls contain Posidonomya becheri 
and Glyphioceras reticulatum, and are of ' P ' age. 
In Bowland itself — the area which must decide the meaning of 
the term — we unfortunately do not yet know the age of the base of the 
Bowland Shales. 
PENDLESIDE GRIT. 
The time value of this division can only be determined from the 
ages of the fossiliferous beds above and below ; as shown below, the 
date will therefore, on Pendle Hill, be '' P ' of Hind and Howe. 
PENDLESIDE LIMESTONE. 
[The upper part of the Shales -ivith- Limestone). 
Recent views are in accord with Mr. Tiddeman's correlation of 
the top of the Shales-with-Limestone (i.e., the Pendleside Limestone) 
on Pendle Hill, with the knolls of S. Craven. The relation is that of 
Cyathaxonia-heds to knoll limestones and can be accurately compared 
Avith the same correlation in the Midland Province (e.g., The Tissington 
Cyathaxonia-Beds with the Thorpe Cloud Knoll). The very inad- 
equate collecting that has as yet been done at this important level, 
suggests that it lies in the zone of Glyphioceras [Sj^henoceras) striatum 
and, therefore, immediately under ' P.' 
