﻿54 MB. T. r. SIBLT ON THE FATTNAL SUCCESSION IN THE [Feb. I908, 



(ii) Sections north of the typical section. 



(a) The Bradwell-Dale section, extending south- 

 wards from Bradwell. 



This section, which is confined to Dg, shows from 150 to ^00 feet 

 of that subzone. The limestones are very variable in character, 

 consisting largely of light-grey or white beds, often oolitic, and 

 including also dark-grey or blue bands. Chert is strongly developed 

 at various levels throughout the section, but there is no development 

 of compact black limestones similar to those of the typical section. 



(6) The Middleton-Dale section, extending west- 

 wards from Stoney Middleton. 



The cliff-sections and numerous quarries in Middleton Dale show, 

 at a rough estimate, rather over bOO feet of Carboniferous Lime- 

 stone. The highest beds exposed, which are thinly-bedded black 

 limestones with abundant chert, include the uppermost part of D^, 

 and probably also the lower part of Dg ; 50 or 60 feet of these 

 are seen. Below these beds, the limestones contain a typical D^ 

 fauna, down to within a short distance of the base of the section. 

 The series below the black cherty beds consists of white, grey, or 

 light-brown limestones, thickly and thinly bedded, very variable 

 in texture. Chert is largely developed at various levels, down to 

 within about 70 feet of the base of the section. 



(iii) Sections south of the typical section. 



(rt) The Gratton-Dale section, near Elton. 



Next to the typical section this is, probably, the most extensive 

 in the area. The exposure is, however, by no means continuous, 

 and the estimate of the thickness of the beds, given below, can only 

 be considered as an approximation. The following is the sequence, 

 given in descending order : — 



Thickness in feet, 



(1) Limestones to top of section. 



The uppermost beds consist partly of thinly-bedded, grey-blue 

 limestones without chert ; partly of hard, black, compact lime- 

 stones, with abundant chert and thin partings of shale. The beds 

 are dolomitized in places. 



The main series consists of limestones, variably white or grey 

 in colour, without chert, but with occasional black beds. Many 

 beds are highly crinoidal 250 



(2) Lava .' 70 



(3) Grey limestones 290 



(4) Yellowish-brown, dolomitic limestones (>30 



(5) Dark-grey limestones, to base of section — 



1240 



