4'24 IIIXD : CARBONIFEROUS ROCKS OF THE PENNINE SYSTEM. 
shire and Derbyshire forming the tectonic centre of the great Pennine 
anticlinal. This mass, from 2,000 to 3,000 ft. thick, whose base 
has never been seen, is practically one mass of limestone, divided 
by very thin partings of shale into beds of stone, which are occasion- 
ally very thick and with very obscure bedding planes. In the quarry 
opposite the High Tor at Matlock and at Coombsdale the officers 
of the Geological Survey describe a thin coal and its underclay in 
the limestone. I have been informed that a piece of Stigmaria was 
obtained in the former locality. 
The upper part of the Limestone is extremely variable, being 
thin bedded, thick, and crinoidal, massive and highly fossiliferous, 
or even cherty at apparently the same horizon in various places. 
But at or near the top is a bed containing many rolled water-worn 
shells and pebbles (?) of limestone, which is fairly constant over the 
w^hole area. At times the top of the limestone series is abrupt and 
sudden, and shales come on at once ; at others there exists a well- 
defined series of passage beds of thin shelly limestones and shales, 
possibly a phase of the rolled shell bed, consisting of more comminuted 
but less rolled shell material. In places the upper 30 or 40 ft. of 
this Limestone Massif must have been a shell bank, for the limestone 
is made up of fossils, many of the shells being perfect, but others being 
slightly eroded ; but, evidently, from the fact that all kinds of fossils 
are present massed and jammed together, not exactly in the place 
where all lived, but while there is no doubt that some species were 
able to and did live on the bank, the shells of others were washed 
there by currents. 
At Castleton and Waterhouses the bed of rolled shells consists 
chiefly of fragments of Produdus giganteus, but this shell occurs 
again in the next 15 or 20 ft. which forms the top of the limestone. 
This line is at once the upper limit of the massive limestone and 
of P. giganteus, for in this district this shell does not appear again 
at any higher horizon. 
The massif of limestone is succeeded by a series of black shales 
and thin limestones, for which I have adopted the name Pendle- 
SIDE Series, with a peculiar fauna of Posidonomya Becheri, P. mem- 
branacea, Posidoniella Imvis, P. minor, Chcenocardiola F ootii, Pterino- 
