CXX PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



deposit : in the Department of tlie Moselle, however, the coal is over- 

 laid by the new red sandstone. This paper was accompanied by 

 a useful map, showing the position of all the workings from Valen- 

 ciennes, westward, to the Pas de Calais, a distance of about 100 

 miles ; and the manner in which the outcrop of each member of the 

 formation, from the lower devonian upwards, is shown by the use of 

 letters, as L D, M D, for lower and middle devonian, DC, D L, Devo- 

 nian conglomerate and limestone, L M L, lower mountain-lim.estone, 

 L C, lower carboniferous, C ^I, coal-measures, deserves attention 

 from its simplicity and eifectiveness. 



The labours of the Geological Society of Dublin have been lately 

 directed to the investigation of the position of the Coal-formation of 

 Ireland, and its relation to the Old Red Sandstone. Mr. John Kelly, 

 formerly one of the most active assistants of Dr. Griffith, and now 

 employed upon the Governm.ent Geological Survey, read a paper 

 upon the subject, which has been published in the Journal of the So- 

 ciety. Conforming to the views expressed by Professor Phillips in his 

 " Geology of Yorkshire," Mr. Kelly represents the carboniferous 

 formation of Ireland as constituting a triple system, characterized by 

 the prevalence of coal, of limestone, and of red sandstone ; and, as re- 

 gards Ireland, he observes that, though its subdivisions differ widely 

 lithologically, the whole system is characterized — 1st, from the strata 

 of which it is composed resting unconformably on whatever rock lies 

 below them ; 2ndly, as being covered unconformably by the overlying 

 rock ; and 3rdly, as being parallel to one another, or lying, as it were, 

 in one bundle. This statement implies that the mountain-limestone, 

 coal-deposits, and old red sandstone are uniformly parallel or con- 

 formable to each other, — a view of the circumstances which, I suspect, 

 cannot be established even in the limited area of Ireland. Of any 

 great deposit of gravel and sand, the formation of which indicates a 

 certain amount of violent action and of progressive movement, it 

 must always be difficult to define the precise epoch, unless some of the 

 organic relics of the period should have been preserved. This is 

 the case in the old red sandstone, and it is only when in the lower 

 beds certain Silurian fossils, or fossils c'osely analogous to them, are 

 found, that the relation to the Silurian becoT.es manifest ; just as in 

 the other case the relation to the carboniferous strata is similarly 

 established by the presence of carboniferous fossiis. On this princi- 

 ple I have elsewhere urged, that, whilst the Old Ked may be consi- 

 dered to graduate downwards into the Silurian, it may equally be con- 

 sidered to graduate upwards into the Carboniferous. Nor is local 

 unconformability or local conformability sufficient to decide, or even 

 to affect, this question. It appears, for example, from Mr. Kelly's 

 statement, that at Lisbellaw a brown stone, or conglomerate, is con- 

 formable to the fossiliferous Silurian grey grits and slates, — this would 

 be a violation of the first of his three great characteristics, were this 

 rock to be considered a part of the Devonian or Old Red Sandstone ; 

 but Mr. Kelly separates it entirely from that formation, and supports 

 his opinion by referring to various points in the South of Ireland where 

 the Old Red Sandstone is seen to cap unconformably a brown sapd- 



