32 WILMORE : THE STRUCTURE OF SOME CRAVEN LIMESTONES. 
limestone iii the middle of the massif and elsewhere, and quite 
as well as I have seen them in the thick white limestone north 
of the fault, e.g., in the neighbourhood of Arnside, and in Derby- 
shire, where there is no distinctive knoll-structure. 
I have not noticed corals to be nearly so common in these 
Clitheroe masses as they seem to be in some parts of the Car- 
boniferous Limestone, in the neighbourhood of Arnside, for 
example. One finds there enormous masses built up of Cyatho- 
phyllum, Lonsdaleia and Lithostrotion ; but that is not so 
in the Clitheroe district, though, of course, we find such genera 
as Amplexus, Zaphrentis, Cyathophyllum scattered amongst 
the shell and crinoid debris. 
In connection with these white limestones there are con- 
glomerates and breccias, which have been the subject of much 
comment and some dispute. To prevent confusion it may be 
well to point out that three types of breccia are found in the 
Craven Lowland country. First, crush breccias, like those noted 
by Prof. Marr at Draughton and at Winterburn ; good ex- 
amples are to be seen at Broughton Fields, in the eastern part 
of the district, and at Foxley Bank in the north-western corner. 
I do not think examples are frequent. Secondly, there arc the 
shell and crinoid breccias already noted. Thirdly, there are 
the limestone breccias, made up of deriv^ed fragments ; most, 
if not all, of these fragments are of Carboniferous Limestone 
stuff and must have been broken off th^ already solid or partly 
solid masses of calcareous deposit. At Worston — Crow Hill 
— such a breccia consists of fragments of crinoids and of echinoids, 
of shells, and of allothigenous bits of crinoidal stuff and solidified 
limestone " paste." This example seems to be interbedded with 
the usual shell and crinoid breccia, and there is every gradation 
between stuff formed exclusively of immediate organic debris, 
and stuff containing little else than derived lumps of matter, 
which was already solidified or partially solidified (cemented). 
This somewhat typical breccia happens to be well seen at 
the front (base) of a knoll, but this is probably accidental, and 
as it is a fairly regularly bedded mass of limestone, the breccia 
belongs to the upper part of the limestone massif. 
