OLD RED SANDSTONE OF WESTERN EUROPE, 429 
At the eastern extremity the junction of the Old Red Sandstone with the 
crystalline rocks is seen to great advantage on the shore of Aberdour Bay 
beyond Dundarg Castle. The metamorphosed slates and greywackes, here and 
there twisted into sharp folds, form a steep rocky bank, against which the later 
red deposits have been formed (fig. 13). At the northern end of the junction a 
coarse brecciated conglomerate a few yards thick, and formed mainly from the 
anderlying rock, constitutes the lowest bed, and wraps round projecting knobs 
of slate. A little to the south this basement conglomerate thins away, and the 
uneven denuded edges of the older rocks are then covered directly by red sand- 
stones, consisting of a granitic sand with many rounded pebbles of granite, and 
abundant angular fragments of the surrounding slates. Sandstone of this 
character, but becoming finer in texture, continues along the bay to the west 
side of the promontory on which Dundarg Castle stands, where it passes under 
a series of dirty red and mottled shales and clays containing abundant calcare- 
sus nodules and lenticular beds of red, and less commonly yellow, cornstone. 
By means of a fault this shale zone is soon thrown out, and red sandstone 
appears on the beach, extending to the Dour Burn, which falls into the middle 
of the bay. This sandstone much resembles that which underlies the shale. 
In great part it is often rather a conglomerate than a sandstone, having a coarse 
granitic paste through which pebbles and especially angular chips of slate are 
scattered or crowded into nests and lenticular bands. As they so closely cor- 
respond to the conglomeratic sandstone below, and pass beneath a similar shale 
zone, it is possible that the two sandstones are the same, though a considerably 
greater thickness of the deposit occurs to the west of Dundarg than intervenes 
between the shale and the slates to the east. At the mouth of the Dour Burn 
the sandstone passes under a series of shales and shaly flagstones of dark brown, 
red, and purple colours, with abundant calcareous nodules in some bands. 
These beds, though soon thrown out by two faults, which bring up the old 
slates, agree so closely with the shale zone at Dundarg that they may with 
probability be regarded as the same. The coast-line for three-quarters of a 
mile is now occupied by slates, schists, and greywackes, until on the west side 
of Strathangles Point another fault occurs, by which the conglomerate is again 
brought in on the face of a tall cliff along a nearly vertical line against the 
slates. This rock, which, there can be little doubt, is the prolongation of the 
conglomeratic sandstone and conglomerate just mentioned, rises between that 
promontory and the fishing village of Pennan, into the noblest sea-cliffs in the 
north of the mainland of Scotland. Vertical walls and huge quadrangular 
buttresses tower above the waves to a height of from 400 to 500 feet. The 
horizontal or gently undulating strata, admirably exposed along these magni- 
ficent natural sections, are seen to consist of the same coarse angular detritus, 
with seams of finer sandstone. The mural character of the precipices is doubt- 
VOL, XXVIII. PART II. 5 T 
