IN THE LOWER OLD RED SANDSTONE OF SCOTLAND. 221 



felted vegetable remains. In one or two places (notably Cameron 

 Plantation near Balloch) lenticular patches of anthracitic coal a few 

 lines in thickness have been observed. The flagstones are generally 

 grey, with a more or less distinct greenish tinge, and contain pellets 

 of shale and sparsely scattered lobbies of white quartz. Felspathic 

 and siliceous granules contribute in about equal proportions to the 

 composition of the flagstones. The flags, which are divided by 

 green, grey, blue and purple shales, are extensively used for building- 

 purposes in the neighbourhood (the Duke of Montrose's principal 

 seat, Buchanan House, for example, being built of them), and occa- 

 sionally for pavement, although they are less hard and durable than 

 the Arbroath and Caithness flags. In former days they were fre- 

 quently employed as tilestones ; but this heavy roofing-material has 

 entirely given place to the slates of the Highland border. 



We may now shortly trace the flagstone group from the Braes of 

 Doune southwestward to the Clyde. 



The fall of the ground from the Braes of Doune to the river Teith 

 at once denudes the flagstone group of the overlying sandstones and 

 conglomerates, so that in the valley the centre of the trough is 

 formed solely by the flagstones. This continues to be the case till 

 the raised beach-deposits of the Carse of Forth to the south of 

 Thornhill obscure the solid geology. 



jSouth of the Carse of Forth, the Lower Old Red Sandstone area is 

 rapidly narrowed by the south-westward continuation of the fault 

 which bounds the Ochils on the south side. Extending from Kippen 

 to Cardross Park on the Firth of Clyde, this fault brings, on its 

 south-eastern side, the Calciferous Sandstones down against the 

 Lower Old Red Sandstones. On the south side of the Carse of 

 Forth, brown felspathic sandstones, probably representing those of 

 group B, overlie the Flagstone group, which here dips to the (south- 

 east. The Flagstone group thickens considerably towards the Clyde, 

 and between Geilston and the foot of Loch Lomond (where no other 

 member of the Lower Old Bed Sandstone formation is seen) it cannot 

 be less than 2000 feet in thickness. Here the axial beds of the 

 synclinal trough are concealed by the fault which throws down the 

 Calciferous Sandstones against the Lower Old Red Sandstone. The 

 Lower Old Red Sandstone does not reappear on the southern shore 

 of the Firth of Clyde. 



5. Locality. — Quarry, 2| miles S. by "W. of Braendam House, E. of 

 Callander, and S.W. corner of Muir Plantation, near Braendam 

 House. 



6. Other Plant-remains. — Fragments of plants have been found 

 in the Lower Old Red Sandstone at the following localities : — 



(a) Buchanan-Castle Quarry, near Drymen, Stirlingshire, in a thin- 

 bedded sandstone. A small stem (?), nearly three inches long by 

 two or three lines wide, with portions of the black carbonaceous 

 matter into which it has been converted adhering, and a good deal 

 wrinkled. 



(6) Old Quarry at Small Reservoir, near Kilmahew , north of Cardross, 

 Stirlingshire, in a light- coloured thin-bedded sandstone. A stem 



