157 FERMOR: GEOLOGY AND COAL RESOURCES OF KOREA, C. P. 
to W. 35° N. At this particular point the sill has intruded 
itself between the topmost layers of the Talchirs almost at the 
junction with the overlying Barakars. To the E. N. E. of this 
point the sill seems to be delinitely intrusive iu the Barakars 
throughout practically the whole of its course, .whilst to the west 
and south-west the sill rests partly on the Talchirs and partly 
on the Barakars. It will be noticed from the map that some 
of the dykes are represented as definitely joined up with this sill 
and there can be no reasonable doubt that they represent the 
fissures through which the molten magma ascended. The eleva- 
tion of the base of the sill where it rests upon the underlying 
rocks is very variable ; thus on the Sanhat Ghat road leading 
from Baikanthpur to Sanhat, N. E. of Buskata H. S., this height 
was measured as 2,435 feet. At the point near Nagar above 
referred to, this base is at only 1,960 feet. On the south slope 
of Kuro hill (2,496 feet) south of Nagar it is at about 2,350 feet ; 
in the Kurasia nala about 5 miles further south-west the dolerite 
base is seen at 1,927 feet, quickly rising to about 2,450 or 2,500 
feet on Kurasia hill (a2,847) ; whilst, finally, 5 miles further 
south-west, I discovered a very small outlier on the top of Bar- 
tunga Hill with its base at about 2,900 feet. These differences 
in elevation are, no doubt, partly due to the eft'ects of denudation 
upon a dipping bed of rock ; but they are undoubtedly partly 
due to the sill gradually rising or sinking in stratigraphical 
position. 
The main channel of eruption of this sill, judging from Hughes' 
map, is probably the dyke indicated as stretching at intervals 
for some 26 miles from Sardih on the east, through Sarola, to a 
point north of Bouridand on the west. It is interesting to notice 
that these doleritic dykes are nowhere shown on Hughes' map 
as piercing the Archaean rocks. This may be due to the fact 
that Hughes and Hira Lai were chiefly studying the Gondwanas 
and therefore did not devote any more attention to the Archaean 
inliers than was necessary to delineate their outlines ; or it may 
have some special meaning not yet discovered. The striking 
case south of Siroli, where the dyke is shown as stopping short 
on either side of the Archaean inlier, where the Hasdo river 
crosses it, lay in my way. Unfortvinately heavy storms had flushed 
the Hasdo into semi-flood and I was able only to investigate the 
western shore. Here, however, I found the dyke actually extend. 
