368 PROFESSOR GEIKIE ON THE 
Orkney Islands are presented to us the deposits of the deeper or at least more 
open waters of the lake. In the other districts we meet with the littoral accu- 
mulations of that great water-basin. 
3. DESCRIPTION OF DIFFERENT DISTRICTS. 
A. Caithness and Sutherland. 
1. Structure and Sections. 
The county of Caithness, in its geological structure as well as in its 
scenery, differs essentially from any other county in Scotland. It may be 
appropriately described as a wide table-land of triangular form, sloping up 
into the Sutherlandshire mountains on the south-west side, and truncated 
by the sea on the northern and eastern margins. When seen from any 
elevation beyond its borders, such as Ben Griam or Morven, this table-land, 
of which the average elevation may be taken at probably less than 350 feet, 
spreads out as a wide flat expanse of black peat rising here and there into 
gentle swells or ridges and sinking into numerous tarns and lochs. The geologist 
who tries to penetrate this interior soon finds himself beyond the limits of cul- 
tivation ; roads, quarries, and every ordinary artificial opening into the rocks 
disappear; over broad spaces there are no streams save the dark brown runnels 
which trickle from the peat mosses, and carry the discoloured drainage of 
these barren wastes to the sea. Fortunately, however, the deep and wide- 
spread pall of peat gives way along the coast-line to some of the most magni- 
ficent ranges of mural precipices to be seen anywhere in Britain. There the 
obscurity of the interior is amply compensated by the full display of almost 
every bed and layer in the formation from base to summit. The angles of 
inclination are usually low, so low indeed that any one accustomed to the Old 
Red Sandstone in the central and southern counties of Scotland is rather 
inclined to look upon the Caithness strata as almost horizontal. Gentle anti- 
clinal and synclinal folds repeat the same beds again and again, while a further 
reduplication is caused by small faults. But on the whole one cannot fail to 
be impressed by the general absence of disturbance in the Old Red Sandstone, 
not in Caithness only, but everywhere to the north of the Grampian range—a 
character which does not extend to the same system of rocks on the south side 
of that ridge. Were it not indeed for the occurrence of these faults and undu- 
lations, which either throw out or repeat portions of the strata, and for the 
absence of any very readily recognizable bands, which might serve as horizons 
and thereby allow the actual extent of the dislocations to be measured, there 
would be no difficulty in constructing a detailed section showing every minute 
variety in the stratification of many thousand feet of rock. | 
The eastern coast cuts the Old Red Sandstone of Caithness from its base to 

