124 PROCEEDINGS OF SOCIETIES. 



naghan, and Fermanagh. Those three types happen also, on both sides 

 of the Irish Channel, to correspond in the general geological strike, and 

 the rocks of Dublin are a continuation of the rocks of Lancashire, con- 

 nected, too, by a link in the Isle of Man, all of the same type. These 

 three English types are well described in Phillips's " Geology of York;" 

 and in the middle type he not only describes accurately the passage from 

 the limestone into the overlying coal shales, but the country afforded 

 him opportunities of giving actual measurements of the thicknesses of the 

 alternating bands of shale and black limestone in several sections. Such 

 opportunities, however, do not offer in Dublin, as the country is low, 

 flat, much broken up by faults, and covered with drift. 



With the Dublin district I begin by stating that there is a detached 

 patch of the bottom of the coal shales at Kiltegan, about a mile north- 

 wards from Clonmel. To the south and south-west of Fethard, at Bar- 

 retstown and Gurrane, there are two of the same kind ; east of Cashel 

 are two more of a similar kind ; then comes the Killenaule coal district 

 and the Castlecomer coal district. All these belong to the Coal series, 

 and rest directly upon gray limestone. I refer to them for the purpose 

 of showing that, with the exception of the passage beds at the top of the 

 limestone, the upper shales of Dublin are precisely similar in position, 

 as they are in character, with those coal shales in the south ; and the 

 shales in the counties of Kildare, Meath, and Westmeath, coloured on the 

 "Map" as calp, the same. / 



Those detached patches in Tipperary bear evidence that denudation 

 to a great amount took place over the face of the country, for, being next 

 over the limestone, they are, of course, as just stated, belonging to the 

 very bottom of the coal shales, the upper part having been carried away. 

 In the north of the county of Dublin there is still a good thickness of 

 those shales remaining — I should say, south of the Naul, 1100 or 1200 

 feet — and ironstones and sandstones, similar to those at Killenaule and 

 Castlecomer accompany them. At Balrickard a gray sandstone was 

 worked for the railway viaduct at Balbriggan. Sandstone occurs at 

 Garristown; to the south-east of Slane is a band, coloured on the "Map" 

 as calp sandstone, and another, similar, near Navan, and many smaller 

 ones, as may be seen by reference to the " Geological Map." 



While on this part of the subject I may mention that, when employed 

 on public works in the south of Ireland, I opened dozens of quarries in 

 the coal country about Abbeyfeale, to get sandstone for the bridges and 

 retaining walls. I am well acquainted with their appearance. Some 

 time ago I visited a sandstone quarry near Navan, opened for the use of a 

 railway bridge at Beauparc, and there, at a glance, recognised the litho- 

 logical character of the quarries at Abbeyfeale : the same in colour, in 

 hardness, in black shale partings, and alternating beds — the same in 

 everything. 



For those who may wish to see a clear distinction between those 

 lower and upper shales there is a good opportunity near Malahide. The 

 Carboniferous Slate is seen dipping under the gray limestone, and both 

 in contact at the Martello Tower of Portmarnoek, proving it to be the 



