230 DR JAMES GEIKIE ON 
In Tindholm coal and clay are found irregularly associated with basalt. 
FORCHHAMMER’S description, which is not very clear, would lead one to suppose 
that the beds are much disturbed, interrupted, caught up, and enclosed in the 
basalt. He gives a section in which basalt is seen terminating abruptly 
against clay, and in the latter he says there are sporadic lumps of basalt. 
Perhaps these “lumps” may be only veins seen in cross-section,* Many of 
the basalt-dykes which intersect the sea-cliffs of the northern islands are 
accompanied by what seem to be irregular lumps of black basalt completely 
isolated and embedded in the surrounding dolerite and tuff—but these are 
clearly only the sectional faces of smaller veins proceeding from the main 
dyke (see Plates XIV. and XV. figs. 14 and 15). 
According to FoRCHHAMMER, the coal-beds of Tindholm are perhaps on a 
different horizon from those of Myggenes. 
6. Subsequent or Intrusive Basalts of Suderoe.—Basalt occurs intrusively in 
Suderée both in the form of sheets and veins or dykes. Very fine exposures 
of a sheet of prismatic basalt 30 to 50 feet thick are seen on the shore at 
Frodbée, where the rock is fine-grained and of a dark blue colour. It shows 
a few small round vesicles, which are usually filled with calespar. The columns 
of this basalt vary in diameter from a few inches up to1 foot 6 inches and 2 
feet. They are often extremely regular, and sometimes show beautiful radiat- 
ing forms. Similar prismatic basalt occurs at Kvannabotnir. There and at 
Kvanhauge irregular dykes, veins, and sheets are intruded among the aname- 
sites, tuffs,and shales. All these dykes and sheets are evidently part and parcel 
of one and the same irruptive sheet, which may be traced in the cliffs round 
into Qvalbéefiord as far as Tiddnenees, and a similar irregular mass occurs on 
relatively the same horizon on the opposite side of the fiord at Qvalbée, from 
which place it continues along the coast for some distance down the fiord. At 
one place to the north-east of Qvalbée the veins and dykes proceeding from 
this mass are beautifully displayed in the cliffs as they traverse a bright red 
rock, which is probably tuff (Plate XIV. fig. 10). Close to Qvalbée the basalt is 
quite prismatic. It is most probable that all these intrusive basalts belong to 
one and the same intrusive sheet. At Frodbde the rock occurs a little below the 
horizon of the coal-beds (see Plate XIII. fig. 1), while at Kvanhauge the latter 
are highly confused and disturbed by it; and it continues at the same level all 
round the coast to Tiddnenzes. On the opposite shore of the fiord it reappears 
at Qvalbée, where it seems to occupy the position of the coal—the coal never 
having been observed at this place. These phenomena are quite in keeping 
with what we know of the intrusive basalt-rocks of the Scottish coal-fields, 
which are peculiarly prone to occupy the position of coal-seams. Not un- 
usually our miners find some particular coal destroyed over a wide district by 
* TREVELYAN says that the coal and clay of Tindholm are “apparently enclosed in the trap.” 
