2 TRANSACTIONS-PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
To use a common expression of the tourist guide-book, all who 
travel from Perth to Dundee by road, rail, or river, cannot fail to 
be charmed by the varied and beautiful scenic display of the Braes 
of the Carse, and no fairer spot meets the gazer’s eye than Rossie 
Priory, nestling at the foot of the wood-crowned Rossie Hill. 
The Cathedral-looking Priory, from every point of view, is a 
striking landmark, and a decided attraction to the whole of the 
eastern portion of the Braes of the Carse. Rossie Hill, so con¬ 
spicuous a landmark from its isolated position and its wooded slopes, 
backed by the barer Sidlaws beyond, forms the southern boundary 
of what might well be termed a basaltic plateau. This plateau, 
partly on and partly within the confines of our county, is rectangular 
in general outline, and covers an area, roughly calculated, of nine 
square miles. From Rossie Hill it extends northwards for some 
five miles into the parish of Fowlis-Easter. 
This basaltic plateau stands quite distinct and apart from the 
Sidlaws, for it is almost entirely surrounded by the Old Red Sand¬ 
stone. It is, indeed, an igneous island in the midst of an aqueous 
deposit. The plateau is cut into two almost equal portions by the 
stream which has carved out the romantic Den of Balruddery, a spot 
dear to the local geologist, for it is in this den that many of the 
fossil fish of the Old Red Sandstone age have been found. A fine 
collection of these is to be found in Lord Kinnaird’s private geolo¬ 
gical museum at Rossie Priory. The Balruddery Burn has cut quite 
down through the overlying basalt into the sandstones beneath. The 
basalt is to be observed at many points resting on the underlying 
sandstones, thus proving that the overlying plateau must have been 
laid down after and not during the deposition of the Old Red Sand¬ 
stone, as in the case of the Sidlaws. If further proof were required 
to demonstrate that this deposit is younger than the Sidlaws, it could 
be found in the fact that detached portions of the plateau are to be 
found in the Sidlaws themselves, and forming detached hillocks, or 
caps, resting on the underlying porphyrites, as at Littleton Hill and 
Tinkle Top. Castle Huntly is also situated on another of these 
isolated caps. 
Whilst it can be demonstrated that the rock of Rossie Hill was 
erupted subsequently to the deposition of the Old Red Sandstone, 
it is a difficult problem to state when the eruption actually took place. 
It is highly probable, however, that it took place during the latter 
part of the Old Red Sandstone age, and it may have been as late as 
carboniferous times, when our coal beds were being slowly and 
silently deposited. During the whole of that epoch we have ample 
evidence of great volcanic activity. A glance at a geological map 
will at once show that the coalfields of Scotland, and specially of 
