6 Geological Society. 



" Description of a Model of Arthur's Seat and the King's Park, 

 Edinburgh," by J. Robison Wright, Esq.. F.G.S. 



This model was constructed on a horizontal scale of ten inches 

 to a mile, but for the vertical scale double that dimension was em- 

 ployed, to render the crags perceptible to the eye. The included 

 area is between two and three square miles, extending from Edin- 

 burgh on the west to Duddington on the east, and from Holyrood 

 Palace on the north to Prestontield on the south. The author notices 

 in his description the structure and phaenomena successively exposed 

 in proceeding from Edinburgh eastward ; but as the details have been 

 chiefly extracted, ^^•ith acknowledgment, from Mr. Maclaren's pub- 

 lished work on Fife and the Lothians, it is not considered necessary 

 to give an abstract of them. 



"Notes by Mr. Maclauchlan, F.G.S., to accompany some Fos- 

 sils collected by himself and Mr. Still, F.G.S., during their employ- 

 ment on the Ordnance Survey in Pembrokeshire." 



Taking for a base-line the northern boundary of the Llandeilo 

 flags laid down by Mr. Murchison, the author proceeds to describe 

 a section extending from near Llanhuadain on the south, to Dinas 

 Head on the north. At Potter's Slade, a little north-west of Llan- 

 huadain, a conglomerate dips to the northward, and is traceable 

 westward to Ford, and eastward towards Llangan, where a sandstone 

 conglomerate occurs containing Trilobites and shells. Proceeding 

 on the line of section, the conglomerate is succeeded first by sand- 

 stone and sandstone shales, and then at Clarbeston by limestone with 

 carboniferous shales, dipping northward, and containing Graptolites 

 and casts of shells. Similar carbonaceous shales exist on the west 

 of Clarbeston, at St. Catharine's Bridge, near Camrose ; also at 

 Rudbaxton, and on the east at Long Ford, near lilandysilio. They 

 have in some localities been unsuccessfully worked for coal. Grap- 

 tolites have likewise been found in calcareous shales at Robleston, 

 about a mile north-west of Camrose. At Llys-y-fran, north of Clar- 

 beston, the carbonaceous shales are succeeded by roofing-slates, 

 which at Mynydd Castell-bythe (Castell-y-furoch, Ord. Map) and 

 Morfel alternate with trap. On the summit of Mynydd Pontfaen, 

 sandstone with coarse slates occurs, and between the summit and 

 Pontfaen, trap again alternates with slates. The summit of Mynydd 

 Llanllawer consists of coarse-grained, rudely columnar greenstone, 

 flanked on the northern declivity of the mountain by coarse sand- 

 stone of trappean aspect. This rock is overlaid by roofing-slates, 

 which extend nearly to Dinas Head, where a hard conglomerate 

 sandstone, containing crinoidal remains, is exhibited. All these 

 strata are represented in a section as dipping towards the north. 



In Aberreiddy Bay, about twelve and a half miles to the south- 

 west of Dinas, slaty beds with a northwardly dip, and apparently 

 prolongations of the schists on the line of section, contain the Grap- 

 tolilhiis Murchisonii and G.foliaceus of the Llandeilo flags, also nu- 

 merous casts of an Euomphalus, resembling the E. perturbatus of 

 that formation, and a species of Lingula. Although these slates 

 differ in lithological characters from the Llandeilo flags, yet Mr. 



