28 THE OLD RED SANDSTONE. 
stand out like the advanced pickets of the land amid the 
ceaseless turmoil of the breakers. ‘The district, as shown on 
the map, presents nearly a triangular form — the Pentland 
Frith and the German Ocean describing two of its sides, 
while the base is formed by the line of boundary which sepa- 
rates it from the county of Sutherland. » 
Now, in a geological point of view, this angle may be re- 
garded as a vast pyramid, rising perpendicularly from the 
basis furnished by the primary rocks of the latter county, and 
presenting newer beds and strata as we ascend, until we 
reach the apex. ‘The line from south to north in the angle — 
from Morvheim to Dunnet-head — corresponds to the line of 
ascent from the top to the bottom of the pyramid. ‘The first 
bed, reckoning from the base upwards, — tke ground’ tier of 
the masonry, if I may so speak, —is the great conglomerate. 
It runs along the line of boundary from sea to sea, — from 
the Ord of Caithness on the east, to Portskerry on the north ; 
and rises, as it approaches the primary hills of Sutherland, 
into a lofty mountain chain of bold and serrated outline, which 
attains its greatest elevation in the hill of Morvheim. This 
great conglomerate bed, the base of the system, is represented 
in the Cromarty section, under the Northern Sutor, by a bed 
two hundred and fifteen feet in thickness. The second tier 
of masonry in the pyramid, and which also runs in a nearly 
parallel line from sea to sea, is composed mostly of a coarse 
red and yellowish sandstone, with here and there beds of peb- 
bles enclosed, and here and there deposits of green earth and 
red marl. It has its representative in the Cromarty section, 
ina bed of red and yellow arenaceous stone, one hundred 
and fourteen feet six inches in thickness. These two inferior 
beds possess but one character, — they are composed of the 
same materials, with merely this difference, that the rocks 
