Notes on the Geology of South Ferriby. 57 
nature and position of this ‘black band’ and its neighbouring 
marl beds are taken advantage of by the quarrymen who find in 
them a convenient position for boring for the purpose of receiving 
the cartridges for blasting. 
Below the black band is the Lower or Grey Chalk, which is 
 flintless and marly, and above it is the hard ‘ middle chalk,’ with 
flints. The two rocks can be easily separated in quarrying and 
f put to their respective uses. 
Asa mule the upper part of the section is quarried more quickly 
than the lower marly chalk, and there is therefore a ledge on the 
level of the black band, which can be walked along almost all 
the way round the pit. If this has been exposed to the weather 
for some time it is probable that the small round Discoidea 
_cylindrica* will be found in fair numbers on the flat surface, 
‘immediately below the dark marl. With it are associated 
numbers of Terebratule, Iehynchonelle, etc. 
Just above this lower chalk are occasionally found those 
enormous Ammonites, usually little more than casts, (though now 
and then the sutures can be traced) for which the quarries are 
‘perhaps best known to the collector of fossils. Two or three, 
fine examples ornament the entrance to Mr. Walker's house at 
South Ferriby, and a specimen measuring 2ft. 3ins. across’ is 
in our Hull museum. They are however obtained of even much 
_ The black band, which is here about 8 or to inches in thick- 
, has yielded a number of the fossils from which the zone 
ives its name, viz., Belemnitella plena. It has been collected 
all the pits, though strangely encugh the fossil was only dis- 
ered in Yorkshire for the first time so recently as May 1905., 
Phe belemnite can be readily distinguished from its shape, tapering 
towards both ends like a cigar. 
Immediately above the black band the zone of Inoceramus 
iloides occurs, and is fairly full of the mussel-shaped bivalve 
*These are still held to be ‘fossil mushrooms ” “by the quarrymen 
who even cut ‘stalks’ to them in the chalk, giving them a striking 
resemblance to the mushrooms they are supposed to be. 
{See Naturalist July, 1905, pp. 202-203, 
