WILMORE : THE STRUCTURE OF SOME CRAVEN LIMESTONES. 31 
the " sulphury " smell on fracture, which contains abundance 
of Producti. At Swinden Moor, dark grey, well-bedded, almost 
flaggy limestone consists almost entirely in places of Chonetes 
and other deeper water forms. At Broughton fields there is 
a very black shaly limestone crowded with small Brachiopod 
shells, and I have no doubt other workers could multiply such 
instances. 
Some of the shells found are rolled ones, having evidently 
been considerably knocked about on the shallow sea beaches 
before being finally entombed in the shell breccia. The occar- 
rence of similar rolled fossils at Cracoe, Threshfield, Malham, 
and other very fossiliferous localities is well known. This 
does not seem to be the case with the shells and other fossils 
found in the well-bedded dark grey and blacker limestones. 
I have rarely found shells from these to show any trace of wear 
and tear. 
Crinoidal limestones are extremely plentiful in all parts 
of the district. At Twiston one of the " knolls " consists almost 
exclusively of crinoid stems. The stems are often indiscrimin- 
ately heaped together, large stems, half inch or more in diameter, 
being mixed with the smallest possible fragments. And yet 
there is often some rude sorting according to size. It is note- 
worthy that in this immense mass comparatively few plates are 
found and the stalks seldom show that branching which is well 
seen in the crinoidal debris of the more shaly areas. At Worsavv 
— ^the largest and highest of the knoll masses — crinoidal debris 
limestones are well developed. They are perfectly well bedded 
— much more so than the Twiston beds — and large flaggy 
pieces for building the walls of the pastures have been got from 
the south-western exposures. 
On the other side of the Worsaw knoll- mass and at Cro^\^ 
Hill, near Worston, the most westerly of the distinctive knoll- 
like masses, crinoidal fragments are mingled indiscriminately 
with shell fragments of all kinds, and with corals and plates 
and cups scattered here and there. This kind of deposit — 
the mixed organic deposit — is more common than a deposit 
made up exclusively of one class of organism. These deposits 
are also fairly well bedded, quite as well as the masses of white 
