430 PROFESSOR GEIKIE ON THE 
less due, like that of those in Caithness and Orkney, to the joints along which 
the rock weathers, and by means of which huge slices are from time to time cut 
sharply away from their face. Apart from the joints, the conglomerate, as may 
be seen at the highest point of Pennan Head, is apt to weather into little 
aiguilles, like those so often assumed by crumbling cliffs of boulder clay. In 
descending upon the picturesquely placed houses of Pennan, we find that 
the conglomerate passes into a greenish breccia of slate fragments and dips 
eastward. The beds gradually incline to north-east and then to north-west, 
but continue to show a brecciated character, and to consist mainly of angular 
slaty débris, with here and there large rounded blocks of granite, felsite-por- 
phyry, and other crystalline rocks. The Lion’s Head is a fine projecting bluff 
of greenish brecciated conglomerate, pierced by a cave which enters from the 
west side, and issues on the middle of the slope on the east side as a huge chasm, 
called “ Hell’s Lum.” The north-westerly gales which send the breakers against 
the western cliff carry the spray through the passage, and drive it in successive 
clouds out of the opening at the “ Lum.” The conglomerate ends off abruptly 
against a fault which cuts the coast due north from Troup House. Preserving 
to the last its impressive mural escarpment, it rises into a cliff 200 feet high, 
which, owing to the inward slope of the joints, even in some places overhangs 
its base. 
By means of the last-named fault the Old Red Sandstone is once more 
thrown out, and the coast projects into the rugged Troup Head, consisting of 
the old slates and schists. On the west side of this interruption at the fishing 
hamlet of Crovie, the same fault again strikes the shore, and the Old Red Sand- 
stone reappears. From this point to the next headland—the More Head of 
Gamrie—the bay is entirely occupied by that formation, which comes out in 
shore ledges and rises into red cliffs and crumbling slopes. The general dip of | 
the beds inclines towards W.S.W., but a large fault, as was shown by Mr 
PRESTWICH, runs in a south-westerly direction behind Gardenstoun, and has the 
effect of bringing up again on the west side a considerable portion of the lower 
sandstones. Arranged in tabular form the Old Red Sandstone of Gamrie Bay 
appears to consist of the following members :— 
7. Coarse brecciated conglomerate. 
6. Grey and red clays and shales with calcareous nodules containing ichthyolites 20 
to 25 feet. 
5, Thick coarse red brecciated conglomerate, with occasional bands of red sandstone 
above Gardenstoun. 
4, Bright red sandstone, seen to the west of Gardenstoun and to the south-west of 
Crovie. 
3. Dull red and grey shaly flagstones, with lenticular grey calcareous seams and cal- 
careous nodules. 

