392 Mr. Weaver on the Structure of the South of Ireland^ 
can be established in the sequence of the transition forma- 
tions. 
M. Beyrich considers the lower calcareous system of M. 
Dumont as identical with the Eifel limestone. And M. Du- 
mont also places the Eifel limestone in parallel with the lower 
limestone of Belgium, finding below them both the same 
lower quartzo-schistous system reposing on the clayslate tract 
of the Ardennes, and tracing all these formations to the banks 
of the Rhine. In this view, I believe, he is correct. 
The evidence as far as produced leads to the conclu- 
sion, that the north-western and south-eastern flanks of the 
clayslate tract of the Ardennes, together with the succeeding 
lower quartzo-schistous and lower calcareous systems on 
each side, in Belgium and the Eifel, are justly referred to the 
transition epoch. From the same evidence it would also ap- 
pear that the upper quartzo-schistous system is more nearly 
allied to the carboniferous than to the transition series ; and 
I conceive it may be composed in part of alternations of old 
red sandstone with beds of carboniferous limestone *, while 
the succeeding mass of the carboniferous limestone and the 
coal measures follow in their regular order. 
That the whole of these series, extending from the north- 
western flank of the Ardennes to the Belgian coal forma- 
tion inclusive, should have been formerly referred by Conti- 
nental geologists to the transition aera in general is not very 
surprising, since they are commonly represented as forming 
an uninterrupted succession (yet with some exceptions), pass- 
ing one into the other, and as having been subjected to the 
same disturbing forces; while they exhibit also some fossils 
that are common both to the lower and higher members of 
the series. But the old red sandstone of British geologists 
has been usually thought to be wanting in the succession, 
both here and in the corresponding tracts extending hence 
beyond the Rhine into Germany. M. Dumont originally 
conceived the lower quartzo-schistous system to represent the 
old red sandstonef, an idea afterwards abandoned; and which 
has been since also repudiated by M. Beyrich, who justly 
observes, that were we to adopt such a view, we should have 
scarcely anything in the whole Rhenish slate mountains but 
old red sandstone and carboniferous limestone, the latter of 
* This view appears supported by the pertinent observations of M. Von 
Dechen, at p. 484 of his modified translation of M. de la Beche’s Manual, 
in which he refers to the beds of red conglomerate which occur on the 
Meuse near Lustin and Profondeville, at Hayoux, south of Huy ; on the 
Vesdre near Pepinster, and on the Vichtbach at Binsfelser Hammer, 
t In his Memoir on the province of Liege, p. 67- 
