NATURAL HISTORY SOCIETY OF GLASGO^V. 137 



typical Carboniferous limestone series of other tracts of Ireland. 

 This feature, he says, was pointed out long ago by Dr Griffith. 

 The late Professor Jukes, in his " Manual of Geology," also says, 

 that in tracins; the Carboniferous series from the central 

 districts of Ireland northwards, the beds become more complicated 

 and sub-divided as we proceed from south to north. The Calp 

 limestone becomes more purely an earthy deposit, and in its 

 middle portion the shales are split up by a considerable group of 

 sandstone beds, sometimes containing traces and thin seams of 

 coal. This sandstone group, I may also point out, is a feature in 

 the Possil coal series in this district, being the repository of the 

 best quarries of this rock in the neighbourhood of Glasgow. 



What Mr Hull means to indicate, and, indeed, has been the 

 first to point out, is the close relationship of this coalfield in the 

 North of Ireland to that of the West of Scotland ; and I think he 

 has established this clearly, both by lithological and palaeonto- 

 logical evidence. In the West of Scotland the great bed, or series 

 of beds, a thousand feet or more in thickness, forming the typical 

 Carboniferous limestone of many tracts in England and Ireland, 

 no longer prevails. With us the limestone series is split up into 

 a dozen or twenty beds, parted by strata of coal, ironstone, 

 sandstone, and shale, and forming a lower and upper series. Few 

 of the limestone beds, even in the district around Beith, in 

 Ayrsliire, where they attain their greatest development, reach 40 

 feet in thickness ; while in many parts of our coalfield they do 

 not average more than from one to five or six feet, many of the 

 beds being of an earthy or impure character. 



Those interested in the physical causes which have brought 

 about this unequal distribution of the limestone strata in the 

 coalfields of Great Britain and Ireland will find an able and 

 interesting paper on the subject by Mr Hull, in the Proceedings 

 of the Geological Society of Glasgow, vol. iii. It is of geological 

 interest also to note that as the Carboniferous strata are traced 

 northwards through the various counties of England, they, like 

 those of Ireland, begin to take on the Scottish types of deposition. 

 Professor Jukes says that the limestone series in the North of 

 England eventually begin to contain beds of sandstone and coal, 

 and that, finally, farther north the whole group becomes a great 

 series of coal measures, containing interstratified limestones in its 

 lower part only. 



