250 
THE TERTIARY VOLCANOES 
BOOK VIII 
along the sea-precipices, each excessive sheet of basalt can be counted from 
base to summit, and followed from promontory to promontory (Mgs. 284, 286). 
In the district of Trotternish, the basalt hills reach a height of 2360 feet. 
Further west, the singular flat-topped eminences, called “ Macleod’s Tables ” 
(Fig. 283) ascend to 1600 feet. 
Along the western side of Skye, the basalts descend beneath the level of 
the Atlantic, save at Eist in Duirinish, where the Secondary strata, with their 
belt of intrusive sills, rise from underneath them, and at the Sound of Soa, 
where they rest on the Torridon Sandstone. Along the eastern side, their 
base runs on the top of the great Jurassic escarpment, whose white and 
yellow sandstones rise there, and on the east side of Eaasay, into long lines 
of pale cliffs. To the south-east, the regularity of the volcanic plateau is 
Fia. 283. — Terraced Hills of Basalt Plateau (Macleod’s Tables), Skye. 
effaced, as in Mull and Ardnamurclian, by the protrusion of extensive 
masses of eruptive rocks constituting the Cuillin and Eed Hills, east of 
which the basalts have been almost entirely removed by denudation, so as to 
expose the older rocks which they once covered, and through which the 
younger eruptive bosses made their way. This is undoubtedly the most 
instructive district for the study of that late phase in the volcanic history of 
Britain comprised in the eruptive bosses of basic and acid rocks. 
The magnificent plateau of this island has been so profoundly cut 
down into glens and arms of the sea, and its component layers are exposed 
along so many leagues of precipice, that its structure is perhaps more com- 
pletely laid open than that of any of the other Tertiary volcanic areas in 
Britain. It is built up of a succession of basalts and dolerites of the usual 
types, which still reach a thickness of more than 2000 feet, though in 
this instance, also, denudation has left only a portion of them, without any 
evidence by which to reckon what their total original depth may have been. 
In rambling over Skye, the geologist is more than ever struck with the 
remarkable scarcity and insignificance of the interstratifications of tuff or of 
any other kind of sedimentary deposit between the successive lava-sheets. 
One of the thickest accumulations of volcanic tuff and conglomerate has 
already been referred to as occurring on the south side of Portree Harbour, 
where it attains a depth of about 200 feet. As it is in immediate connection 
with its parent vent, it will be more fully alluded to in Chapter xli. 
Here, as is so generally observable among the basalt-plateaux, traces of 
