172 



DR B. N. PEACH AND DR J. HORNE ON 



group, composed of gray, white and yellow sandstones, black and blue shales, oil-shales, 

 occasional thin coal-seams, clay ironstones, and thin limestones. The palseontological 

 researches of Dr Traquair, Mr E. Etheridge, jun., the late Mr Kirkby, and others, 

 have shown that while the fauna points mainly to estuarine or brackish water 

 conditions, there are marine bands particularly in Midlothian and the east of Fife 

 which increase in number near the top of the group as we approach the base of the 

 Carboniferous limestone series. Indeed, Mr Kirkby has shown that the fauna of 

 the Carboniferous limestone is present in the upper part of the Calciferous Sand- 

 stone series, so that the boundary line between these two divisions is merely an 

 arbitrary one. 



The normal Cementstone group appears to the north of the Silurian tableland, on 

 the shore at Cockburnspath, where it rests comformably on the cornstone zone of the 

 Upper Old Red Sandstone, the latter yielding scales of Holoptychius nobilissimus. 

 The Cementstones there, as shown by Mr Clough,* are of no great thickness, being 

 truncated by a fault bringing in a subgroup of shales, sandstones, fireclays and thin coals 

 (the latter under one foot thick), which probably represent the Scremerston division of 

 Northumberland. Though on the whole unfossiliferous, the Cementstones there contain 

 a brecciated lamellibranch limestone with plant remains, which recalls similar types in 

 this group in the border region and in the Randerston beds in Fife, to which attention 

 will be immediately directed. Overlying the Carbonaceous group on the shore at Cove, 

 near Cockburnspath, we find sandstones, shales, two thin marine crinoidal limestones, 

 clays, and a thin oil shale.t The late Mr Gunn suggested that the group of the Dun 

 and Woodend limestones might be represented by the marine limestones in Cove 

 Harbour, and that the oil-shale might be the equivalent of that beneath the Oxford 

 limestone.^ But whether this be correct or not, there can be no doubt that the Cove 

 oil-shale represents a stage of the oil-shale group of the Lothians. Unfortunately there 

 is no continuous section from the beds just described up to the marine limestones at 

 Longcraig, Skateraw, and Chapel Point, at the base of the Carboniferous Limestone 

 series, east of Dunbar, but the section so far is a connecting link between the 

 Carboniferous subdivisions of the border region and central Scotland. 



In Midlothian the normal Cementstones appear underneath the volcanic platform of 

 Arthur's Seat, and overlying the Upper Old Red Sandstone in the southern part of 

 Edinburgh. From a recent exposure in the city of Edinburgh, the remains of plants, 

 ostracods, worms, crustaceans and fishes were obtained. The late Mr Kirkby stated, 

 as the result of his examination of the ostracods from this section, that had " the 

 lot been found in Fife it would not have been higher than the Billow Ness beds." 

 (See Plate IV.) 



Above the volcanic platform of Arthur's Seat comes the great succession of strata 

 ranging from the Granton sandstone and Wardie shales to the Hurlet limestone, the 



* Geol. Survey, Sum. of Progress for 1902, p. 121. 

 X Trans. Edin. Geol. Soc, vol. vii. p. 366. 



t Ibid 



