380 
THE GEOLOGIST. 
coal, impure limestone, and sandstones called the " culp " scries, an 
upper limestone, which is overlaid by a representative of the millstone- 
grit, and coal-measure sandstones, and shales with some bad coal. 
Thus we have as follows : — 
1. Coal-measure series. 
2. Millstone grit series. 
3. Upper limestone. 
4. Calp. 
5. Lower limestone. 
G. Carboniferous slates or shales. 
7. Yellow, grey, or red sandstones. 
8. Sandstones and conglomerates. 
Fossils also are not wanting to determine the age of the lowest of 
these rocks, the yellow and red sandstones having furnished shells of 
the mountain-limestone, as the Productus and Orthis. 
The carboniferous slate and lower limestone may be studied in the 
Dublin district, and the geologist should visit the carboniferous slate at 
Poulscadden, near Howth, and also a section near the martello tower at 
Portmarnock. The Old Red Conglomerate may be seen at Shenick 
Island, near Skerries, and the Fosidonomya BecJieri" a thin bivalve, 
strongly marked, may Be obtained in the black carboniferous shales of 
Lough Shinny. We were informed by Mr. Kelly that, although he had 
searched the carboniferous slates in above 150 localities in Ireland, he 
had never found in them cither the " Posidonoraya " or the " Peden 
j)apyraceus,^'' and that these mollusks are, therefore, characteristic of 
the shale beds above the slates. But, above all things, let us advise the 
stranger geologist to apply to the gentlemen connected with the 
Geological Survey and the Museum in St. Stephen's Green for infor- 
mation as to route, &c., before he visits amj locality. It will save much 
time, trouble, and expense, and he will meet with true courtesy and 
attention. 
Our route from Dublin to Dundalk lay through these carboniferous 
deposits, with patches of lower limestone, which, off the Skerry Isles, 
has been denuded from the Lower Silurian slates, and which, with the 
exception of the Drogheda district, occupy the route from the Skerry 
Isles, by Dundalk, to Newbliss. Drogheda deserves a halt for the pur- 
pose of studying the lower limestone and carboniferous slates. We 
