24 
BISAT : THE MILLSTONE GRIT SEQUENCE 
It is not possible owing to lack of exposures to give much detail 
of the Brimham Grit group. There are two strong grit bands, one of 
which is quarried. The quarry baring shows overlying this grit band 
shales which are fairly argillaceous, and to some extent resemble 
the beds at the base of the Cayton Gill series, though they contain 
no fauna. There are one or two thin layers of coaly shale. They 
differ from the barren bed shales in the absence of the strong sandstone 
streaks which pervade the latter, and also their colour is much lighter. 
Taking the whole series into consideration the fact emerges that 
the real clay shales are confined to one or other of the two bands 
which contain a fauna, and thus it would appear that the conditions 
which w^ere favourable to abundant marine life usually led to the 
formation of shales of a clayey rather than a sandy type. 
Dr. Hind states that the Colsterdale fauna has a Pendleside 
facies, and it appears to be a question for further investigation whether 
these lower beds are not really the northern equivalent of the Pendle- 
side shales further south. 
In conclusion, thanks are due to Dr. Wheelton Hind for the 
identification of the fauna, and to the officials of the Leeds, Harrogate, 
and Bradford Corporations for permission to visit tips and for informa- 
tion as to sections. 
