175 FERMOR: GEOLOGY AND COAL RESOURCES OF KOREA, C. P. 
torted veins is shown in PI. 24, fig. 2. The veins probably 
indicate fissures in the coal, produced by some earth movement 
and filled in by material broken from the overlying sandstone. 
The patch may be of similar origin, but it is difficult to picture 
to oneself the actual modus operandi of its formation. 
Lithologically, by far the greater proportion, probably at least 95 
, per cent., of the Barakar series consists of 
Lithological charac- f , , • . . ^ ^ ^ ^m. 
loi-K and peculiarities of felspathic sandstones, in which the felspar is 
the Barakar sandstones, ^j^j^g ^^^^ decomposed. The typical variety 
is porous, friable, coarse-grained, massive, usually false-bedded, and 
of a light grey to cream colour. In addition to the quartz and 
felspar, the rock also contains scales of muscooitc, though these 
are usually scarce and sometimes, also, minute dark grains, which, 
judging from the black sand sometimes found, consist mainly of 
nuKjnetite, though some particles suggest decomposed hiotite. In 
these black sand there is also an abundance of grains of pink 
(jarmt, which must, therefore, also occur in the sandstone, at least 
in places. 
This sandstone weathers with a rough, light-grey, rounded 
surface, on which any structures, such as false-bedding, are 
excellently picked out. At many localities, especially in the 
neighbourhood of Chirmiri, the weathered surface has a tesselated 
appearance, exactly like that seen in sim-dried muds in river-beds, 
and in spite of the arenaceous character of the rock it seems 
difficult to avoid the conclusion that this network of cracks repre- 
sents sun-cracks (Plate 25, fig. 1). 
At other places the surface of the sandstone is traversed by 
a network of thin raised ridges, a fraction of an inch to an inch 
high. They are doubtless due to slight cementation of the sand- 
stone along certain lines, but I could not detect any lithological 
dift'erence. 
In many places the sandstone contains ferruginous additions. 
These usually take the form of spherical concretions from | to 2 
inches in diameter, but sometimes up to 6 inches across. Fre- 
quently they weather out and lie loose in large numbers at the 
surface. When one of these is fractured it is found to consist 
of a harder outer shell of limonite or ochre-cemented sandstone 
with an inner core of softer un-impregnated sandstone. One of 
these concretions (at the Karauli Dhar coal exposure, in the over- 
lying sandstone) was cemented centrally by pyrite. Where still in 
