Bie PROFESSOR GEIKIE ON THE 
strata of the east side. From the fault on the west side of Duncansbay Head, 
an admirable section can be traced, partly in shore-reefs and partly in low but 
highly picturesque cliffs, westward to the fault at Brough, where the flagstones 
are thrown out by a fault which brings down the upper yellow and red sand- 
stones against them. To the west of this interruption, however, they resume 
their position at Castletown, whence they continue without intermission to 
form the coast-line westwards for about twenty-five miles, rising here and there, 
as at Holburn Head, Brims Hill, Sandside Head, and Bighouse, into magnifi- 
cent mural precipices between 200 and 300 feet in height. In no part of the 
northern coast does the lower or red portion of the Caithness Old Red Sand- 
stone appear, nor do we apparently ever reach there even so low a position as the 
massive sandstones and flagstones of Wick. The highest visible members of 
the flagstone series occur about John o’ Groat’s House. A steady easterly 
dip is traceable along that part of the coast-line with one or two trifling un- 
dulations for seven miles. But the angles of inclination are low, seldom rising so 
high as 25°, and usually less than 15°. At the eastern or upper end of the sec- 
tion occur some red sandstones with flagstones and shales; these are under- 
laid by flagstones at Huna, below which lies a second zone of red sandstone, 
forming the west side of Gills Bay. Flagstones and shales succeed, rising at 
first with a steady easterly dip, and then bending round to north-east and north. 
At Harrow the north-easterly inclination becomes predominant, and it continues 
thence by Scarfskerry to Ham ; while the angle of dip rises to from 30° to 50°, 
These are by far the most extensively disturbed beds on any part of the Caith- 
ness coast. Some sharp folds and crumplings occur, particularly between Scarf- 
skerry and Sir John’s Castle. At Ham the strata arch over towards the west, and 
the series is repeated as far up as the portion which lies between Scarfskerry 
and Harrow. The fault at Brough brings the section to an abrupt close. ‘The 
total thickness of strata between Duncansbay Head and Brough must exceed 
8000 feet. Probably the lower portions represent the higher parts of the Latheron 
synclinal beds. If we suppose 1000 feet of them to be thus representative, we 
obtain a total thickness for the Caithness flagstones of at least 16,000 feet. 
Passing to the coast sections west from Dunnet Head, we find a succession | 
of flagstones of which the general dip is towards north-west, at angles varying 
from 15° to 20°, the average being apparently from 8° to 10°. In this portion 
of the traverse a depth of probably not far short of 4000 feet of flagstones 
may be seen. But beyond Holburn Head, owing to the want of correspondence 
between the trend of the coast and the strike of the rocks, a gradual ascent is 
made through at least 800 or 900 feet of additional flagstones. Hence to the 
west of Dunnet Head a thickness of about 4800 feet of flagstones may be seen 
until their top dips under the waters of the Atlantic. There can be little doubt 
that this mass of strata is, on the whole, a repetition of those found to the east 

