in the Vicinity of Manchester. 247 



Three of the limestones are worked at Ardwick for the lime, 

 viz. the " Four- Feet Mine," the " Yard Mine," and the main 

 or " Three- Yards Mine." There seems to be little difference 

 between the qualities of these, their chemical constitution as 

 well as general appearance being very similar. 



Although I have given the average thickness of the lime- 

 stones in the section, their exact thickness cannot always be 

 estimated, owing to their being divided into layers with irre- 

 gular seams of clunch. These interposing clays are not much 

 liked by the miners, being unfavourable to their process of 

 blasting, by diminishing the extent of the fall. 



This clunch, which forms an important feature in the vici- 

 nity of the limestones, consists of a dark brown clay, irregu- 

 larly tinged with a bluish green substance. It is found in 

 connexion with all the layers, and is often of considerable 

 thickness. 



Sect. V. Mineralogical Character of the Limestones. 



The most striking character of the whole of these limestones 

 is the singular conglomerate appearance they present. This 

 is more or less visible in all the strata, but more especially in 

 the first, or Four-Feet Mine. A seam of variable thickness, 

 generally about ten inches, passes along the lower part of this 

 limestone, possessing the conglomerate character in so striking 

 a degree that the miners can always recognise it where it 

 appears, although it is sometimes interrupted ; they know it 

 by the name of Maxfield, a corruption of Macclesfield : the 

 name has no meaning in it, except from a local circumstance 

 of no importance. 



The limestone is generally of a light gray colour, often 

 tinged with red: where the mottled appearance presents itself^ 

 the matrix is of a darker red or gray, and the imbedded frag- 

 ments of a lighter hue, the ordinary colour of the stone. 



All the limestones are liable to slight variations of colour, 

 even in the different divisions of the same " mine," being 

 sometimes of a dirty gray and sometimes of a reddish yellow. 

 The lowest portion of the Yard Mine almost approaches to 

 black. 



The shales and clays between the limestones vary so much 

 that a detailed description of them would be difficult. They 

 are found of every variety, from a hard sandstone to a fine- 

 grained strong clay or marl, which latter sometimes contains 

 organic remains, as above the " Four- Feet" seam on the bank 

 of the Medlock, where it contains an Unio abundantly, and 

 about sixty yards above the main or Three- Yards seam it is 



