500 C. FE. de Rance—Sections around Southport. 
V.—NortTEs oN GEOLOGICAL SECTIONS, WITHIN Forty Mixes Ranpivs 
oF SouTHport.! 
By Cuartes E. De Rance, F.G.S., F.R.G.S8., A.I.C.E. 
TRIKING a radius of 40 miles from Southport, the line will be 
h} seen to intersect the sea-coast near the Silurian districts of 
Ulverstone in North Lancashire, and Colwyn Bay in North Wales. 
The succession in both cases is very similar, Denbighshire Grits and 
Flags of the one area corresponding in time to the Coniston Grits 
and Flags of the other; and just as the Silurians of the Lake District 
are overlaid by a fringe of Carboniferous Limestone, so the Silurians 
of Diganwy are overlaid by the Carboniferous Limestone of the Great 
and Little Ormes Head. Laid upon a floor of Silurian rocks, the 
Carboniferous Limestone may be regarded as extending continuously 
under the Irish Sea, and underlying the various Carboniferous and 
Triassic rocks now occupying Lancashire.” 
The whole of the Carboniferous rocks have been folded, and con- 
torted, and subsequently denuded before the deposition of the later 
rocks, which do not rest always upon the Coal-measures, which have 
been denuded over the whole of the Furness and Fylde districts, 
and also in the country between Southport and Ormskirk. The 
Carboniferous Limestone of North Wales has been made the subject 
of careful study by Mr. G. H. Morton, F.G.8., who has been able to 
trace successive horizons or beds in it; but it appears to be doubtful 
whether these can be traced in the Lancashire exposures—in which 
the upper part of the series is commencing to assume the type 
called the Yoredale series by Prof. Phillips, in which the lime- 
stones are intercalated with intervening beds of shale and sandstone, 
which gradually increase in importance in proceeding north, until 
the limestones form by far the smaller vertical thickness of the 
entire mass. Near Sedburgh good sections of the base of the Car- 
boniferous Limestone are seen in the banks of the Hebblethwaite Beck, 
a tributary of the Rawthey, sometimes the Lower Limestone Shales 
are present, and in this case they rest on the so-called Old Red Con- 
glomerate, which is directly overlaid by the Limestone when the 
shales are absent, the conglomerate forming simply the “ local base” 
of the Carboniferous Limestone, as in North Wales, where Mr. 
Morton has clearly made out it forms the base of the Middle Lime- 
stone beds, when the Lower Limestones are absent. 
Prof. Phillips, in a paper on the formation of valleys near Kirkby 
1 Read before Section C at the British Association, Southport Meeting, 1883. 
g 
2 Detailed observations on the district will be found in the following Memoirs of 
the Geological Survey:—The Burnley Coal-field ; The Country Around Wigan ; 
The Country Around Bolton; Superficial Deposits of South-west Lancashire ; ‘he 
Country Between Liverpool and Southport; The Country Around Southport, 
Lytham, and Southshore ; The Country Around Blackpool and Fleetwood; and in 
the Maps which these Memoirs illustrate. 
