THE GEOLOGY OF THE FAROE ISLANDS. 235 
of tuff—the highest bed visible being perhaps some 1500 feet or so above the 
sea-level. Again, in the fine mural cliffs and bare rugged slopes of Skiellinge 
Field, as viewed from H@i at the head of Kollefiord, some thirty beds of basalt- 
rock and tuff-partings were visible, which would give an average of about 80 
feet for each bed. Some of the beds, however, were considerably under that 
thickness, while others could hardly have been less than 120 feet or even more. 
None of the bedded dolerites that we saw was so markedly columnar as the 
more typical of the anamesites of Suderde. Now and again, however, we 
observed a rude approximation to columnar structure, and the rocks were very 
generally traversed by strong master-joints at right angles to the plane of 
bedding. 
8. Bedded Tuffs of the Northern Islands.—The tufts of the northern islands 
are precisely similar to those of Suderée, and they need not therefore be 
specially described. I may merely state that we never chanced to come across 
any clunch or clay similar to that with which the coals of Suderée are inter- 
bedded, and no trace of coal has ever been met with in the islands at present 
under review. The thickness of the tuff beds is very variable ; sometimes they 
consist of mere lines, while in other cases I saw im the cliffs beds which may 
have exceeded 100 feet in thickness. It is just possible, however, that these 
tuff-like beds, which were merely observed as we boated past, may have been 
earthy decomposing dolerites. Now and again I saw a tuff thin out as in the 
sea-cliffs near Gritenaes in Stromée (see Plate XIV. fig. 13). But upon the 
whole the tuffs are less conspicuous than the dolerites, for while the latter 
form cliffs and steep faces, the latter usually give rise to slopes and ledges 
which are covered over with débris and vegetation. Some of these slopes 
indicated a thickness of 200 or even 300 feet of soft rock underneath, but 
whether this thickness was all tuff or partly tuff and rotten dolerite, I cannot 
say. In other places again, particularly in the sea-cliffs in the north-west of 
Stromée, the tuff seems to occur as mere thin lines and partings. Some very 
instructive sections showing the rapid alternation of tuff and basalt-rock are 
seen along the southern shores of Fundingsfiord. Here beds of red tuff, varying 
from a foot or less up to several yards, are interbedded with irregularly weather- 
ing dolerite, and show well the undulating surface over which the old lavas 
occasionally flowed (Plate XIV. fig. 12). 
9. Subsequent or Intrusive Basalts of the Northern Islands.—Two sheets of 
intrusive basalt have been described as occurring—the one in Stromée and the 
other in Osterée; but neither of these was visited by us. They are mentioned 
by every writer who has treated of the geognosy of the northern islands. The 
more striking of the two masses is that which is seen exposed along the 
‘western face of Skiellinge Field. It is a columnar basalt of an average thick- 
ness of 100 feet, which traverses the beds obliquely, and is represented by 
