Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/720

		Name of Formation.	Localities.
Essentially Marine.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Stage E. Gannister Beds (Phillips), or Lower Coal-measures.—Flagstones, shales, and thin coals, with hard siliceous floors (Gannister).	South Lancashire, N. Staffordshire, N. Wales and S. Wales.
		Fossils (marine).—Fish, similar to those above (migratory); Molluscs, Goniatites, Discites, Orthoceras, Posidonia, Monotis, Aviculopecten, Anthracosia, Lingula, &c.
		Stage D. Millstone-Grit Series.—Coarse grits, flagstones, and shales, with a few thin coal-seams.	Uplands of Yorkshire, Lancashire, and Derbyshire; N. Staffordshire and N. and S. Wales, &c.
		Fossils (marine).—Similar to those of the Lower Coal-measures.
		Stage C. Yoredale Series.—Shales and grits, passing downwards into dark shales and earthy limestones.	Uplands and valleys of Lancashire, Yorkshire, Derbyshire, N. Staffordshire, Wales, &c.
		Fossils (marine).—Including Goniatites, Aviculopecten, Ctenodonta, Chonetes, Discina, Posidonomya, Productus, &c.
Essentially Marine (except Stage A in Scotland).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Stage B. Carboniferous Limestone.—Massive limestone, passing northwards into several beds, with intervening shales and grits.	Wales, N. & S., Derbyshire, Yorkshire, Cumberland; in Scotland, the Lower or Main Limestone.
		Fossils (marine).—Fish, Crustacea, Molluscs, Crinoids, Corals, &c.; all marine species.
		Stage A. Lower Limestone Shale and Calciferous Sandstone.—Dark shales in some places; grits, conglomerates, and red sandstones and shales in the northern districts.	South Wales, Northumberland, and Durham; in Scotland "Calciferous Sandstone Series."
		Fossils (marine).—Spirifera cuspidata, Rhynchonella pleurodon, &c.
Freshwater Beds.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Basis Upper Old Bed Sandstone.—Yellow sandstones and conglomerates.	S. Wales, Northumberland; Scotland (Dura Den); Ireland (Kiltorcan).
		Fossils (freshwater?).—Not well represented in England.

Thus, taking the lacustrine formation of the Upper Old Red Sandstone as the basis for the succeeding Carboniferous system, we ascend through a vast series of essentially marine strata with oceanic beds, until we reach the top of the Gannister stage, where a change occurs in the character of the fossil forms, and the marine molluscs give place to those of freshwater or estuarine characters. I hope to be able to show that this change is coextensive with the British Isles and at least the neighbouring European Carboniferous districts.

 

Part II.

 

Irish Carboniferous Districts.

A. Southern Coal-districts.

We now come to the consideration of the Carboniferous series of Ireland, taking the districts in the order indicated above.