394 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 16, 



on the Water of Ae west of Glenkiln, and below the summit-cutting 

 of the Caledonian Railway, N.N.E. of Glenkiln. 



About Raecleugh, on the Evan Water, near where the counties of 

 Dumfries and Lanark join, slaty beds occur, which the author has ob- 

 served also at Benbuic (in the western part of Dumfriesshire), near the 

 head of the Dalwhat Burn, in the parish of Glencairn. The surfaces 

 of some of these beds are rippled, and bear Annelid-markings. These 

 slaty beds are next met with twelve miles westward, near Barlae, in 

 the parish of Dairy, Kirkcudbrightshire. Here the rock is identical 

 in character with that at Benbuic, and the faces of some of the beds 

 show ripplings and Annelid-markings, together with Graptolites and 

 Fucoids. 



The author considers this slaty rock to be the equivalent of the 

 Grieston slate, described by Professor Nicol*, and to be the high- 

 est bed seen in Dumfriesshire. But by following up the section af- 

 forded by the Caledonian Railway, he finds the following succession 

 in ascending order : — 



1. Thick and thin greywacke sandstone at the summit-cutting 

 before-mentioned. 2. Grey shales, equivalent to the grey slates of 

 Benbuic and Barlae before-mentioned. 3. A great thickness of 

 black shales, which are different from any rock occurring to the 

 southward, and run E.N.E. into Peeblesshire, where they have been 

 quarried for slate at Wrae in Glenholm parish, and also at Stobo. 

 They are seen again, westward of the Railway at Glenochar, and, 

 though containing no fossils, Mr. Harkness believes them, from their 

 resemblance and position, to be the same as the graptolitic Cairn slates 

 on Loch Ryan, described by Mr. J. C. Mooref. And 4., a. conglome- 

 rate containing fragments of the black shale in great abundance. This 

 is apparently identical with the conglomerate found in a quarry near 

 the base of the hill at Wrae, and underlying the limestone described 

 by Professor NicolJ. The author observes that here the dip of 

 these beds is towards the south, but, as the black shale comes on 

 immediately to the northward with the usual dip, it is probable that 

 the conglomerate and limestone have been let into their present 

 position by a fault. 



Having thus reached the zone of the Wrae limestone, Mr. Harkness 

 dwells upon the close relation of this limestone with that of Craig- 

 head, and with the Silurian rocks of the south-west of Ayrshire, 

 lately described by Sir R. I. Murchison§, and observes that the con- 

 glomerates of Kennedy's Pass, accompanying those Ayrshire beds, 

 contain fragments of Silurian rocks similar to those found southward, 

 and also fragments of syenite resembling that of Cairnsmuir and 

 Loch Doon, which the author considers to be of the same age as 

 that of Criffel. Hence he infers that the elevation of the Silurian 

 rocks to the south had taken place previously to the formation of 

 these conglomerates. 



Mr. Harkness states that he has succeeded in tracing the anthracite 



* Quart. Journ. Geol. Soc. vol. iv. p. 204, and vol. vi. p. 53. 



t Ibid. vol. V. p. 7. t Ibid. vol. iv. p. 203. 



§ Ibid. vol. vii. p. 139 et seq. 



