OLD RED SANDSTONE OF WESTERN EUROPE. 423 
frequently the conglomerates of the region now being described run inland in 
narrow valleys. ’ 
Far up the valley of the Don a much more important outlier extends north- 
wards from this river through the parishes of Kildrummy, Auchindoir, and 
Rhynie, as a strip about nine miles long and a mile and a half broad. This 
tract was laid down upon Maccuttocu’s map; fossil fish like those from 
Lethen, to be afterwards noticed, were said to have been obtained from it as 
far back as 1839, by the Rev. Dr Gordon of Birnie,* and in later years (1854) 
obscure remains of fluted but jointless plants were found there by the Rev. A. 
Mackay.t With the co-operation of Mr B. N. Peacu, I traced the boundaries 
of this area in the summer of 1876, and found it to cast important light upon 
_ the physical geography of the north of Scotland at the time when the Old 
Red Sandstone was laid down. It extends as a narrow belt from the valley of 
the Bogie below the Muir of Rhynie southwards to a little beyond Kildrummie 
Castle, and thus crosses the watershed of Aberdeenshire. It is bounded 
on the west side by a fault, which, running along its whole extent, brings 
| its highest strata against the granite, gneiss, serpentine, and other crystalline 
_ tocks of this part of the Highlands. The east side presents a more sinuous 
boundary, and though the actual junction between the sandstones and the 
underlying metamorphic masses is much obscured by drift, it can be dis- 
| tinetly seen at several places between Cottoun and Westhills, particularly 
on the hill between Cottoun and Druminnor House, where flaggy sand- 
stones and conglomerates lie upon a denuded surface of a decomposing 
| hornblendic rock of the metamorphic series. From the evidence presented 
| by the ground to the south of Druminnor, it appears probable that the 
sandstone series was laid down against a somewhat steep and irregular 
surface, and sometimes at a considerable angle. The best sections are those 
in the water-courses on both sides of the valley between the Rhynie Quarries 
and Lumsden. From.a comparison of these the following table has been 
_ constructed, representing the order of the strata and their approximate 
thicknesses. The total depth of Old Red Sandstone preserved at this locality 
probably measures between 1500 and 2000 feet. 
6. Greenish grey shales, with beds of flagey sandstone. Dryden. 
5, Thick group of hard pale grey and reddish or purplish sandstones, with occasional pebble 
beds, and numerous pipes, “galls,” and irregular veinings of red clay. Rhynie 
quarries, Burn of Craig, about 1000 feet. 
4, Band of diabase-porphyrite, seen between Contlach and Auchindoir Manse. 
order of succession of the strata is given. 
| 
| * Matcotuson, “Quart. Journ. Geol. Soc.” xv. p. 350, footnote, where a brief reference.to the 
| t Op. cit. p. 432. 
