28 
the North of England, and therefore provisionally placed them in a separate 
class which he called ‘‘ Permian Rocks of Salopian type” ; regarding them, 
however, as strictly contemporaneous with the true Zechstein Permians ef the 
North of England. 
These beds are everywhere found to contain fossils of pure Carboniferous 
type, besides thin zones of coalmeasures at different horizons in which thin 
but unworkable coal seams are found. The great mass of the strata consists 
of thick beds of red and mottled marls, interspersed between layers of 
fairly thick sandstones, gritty, calcareous, and conglomeratic towards the 
base, but finer and of a reddish and purple colour towards the summit. 
These upper unproductive coalmeasures attain a very high development 
in North Staffordshire and Denbighshire, and their correlation —I may even 
say identity—has been established in a Paper read before the Geological 
Society on the 20th instant by Mr. Walcot Gibson, F.G.S. 
The following Tables show the correlation :-— 
NorTH STAFFORDSHIRE. 
(WALcoT GiBsoNn, F.G.S.) 
DENBIGHSHIRE. 
(D. C. DaAviEs, F.G.S.) 


feet, feet. 
Keele and Penkhull sandstone Whittington and Erbistock red 
series we Ar aan 3ae sandstones .. ne =a 020 
Newcastle - under- Lyme coal Ifton Rhyn coal series o,, 300 
series os Ae -» 300 Green rocks, grits, conglomer- 
Etruria marls and gritty sand- ates and marls 35 -» 600 
stones ie er .. 1,100 | Thin coals, red and blue rocks.. 220 
Blackband series coal and iron- 
stones ee ee ae 4500 
2,200 1,740 

Absolute uniformity in the distribution of these zones of marls, sand- 
stones, limestones, and coal-bearing beds is not to be expected, and will not 
be found, especially when traced from south to north; but witb a typical 
section like that given by Mr. Gibson, of North Staffordshire, a standard is 
set up which will form an excellent guide to geologists and mining 
engineers. 
Another point which I wish to emphasise is that the colour of the 
contained shales and marls varies considerably from district to district, and 
from zone to zone in the same district; chemically, the difference between 
the blue, green, and red marls is due to the latter containing 9 per cent. of 
peroxide of iron, and the former none; but I wish to suggest that the real 
reason of the difference is entirely of another order—namely, the source of 
supply whence their material was derived. 
In regions adjoining Old Red Sandstone red marls predominate, and 
near Silurian districts, blue; whereas further north, where the Millstone 
grit and Yoredale rocks are in proximity, these coloured marls, though not 
quite extinguished, become quite subordinate, and sandstones, grits, and grey 
shales come more in evidence, as though lower Carboniferous strata had 
been the source of derivation. 
The fact that these strata everywhere contain Carboniferous fossils 
plainly marks their stratigraphical position as being below, and not con- 
temporaneous with true Zechstein Permian. 
But in addition to this, still more direct evidence is furnished by the 
Thurgarton borehole, near Nottingham, where the true Permians are found 
to immediately overlie beds of the same lithological character as those found 
at Keele ; and after these latter are penetrated, a coal series similar to that 
at Newcastle-under-Lyme is met with; for full particulars of which consult 
Mr. Gibson’s Report in the ‘*‘ Annual Summary of Progress of the Geological 
Survey of the United Kingdom for 1899,”’ p. 110. 
i? f 
