170 
MR. C. BARRINGTON BROWN AND PROFESSOR J. W. JUDD 
Here they are of finely foliated grey-and-wliitish gneiss somewhat decomposed, 
in bands of from 10 to 20 feet in thickness. The last one, where further ascent was 
rendered difficult by the precipitous nature of the ridge, was a coarse white granular 
gneiss, containing little mica, but with large nodules of garnet. Near the top of the 
pass is crystalline limestone in the gneiss, occupying a width of 50 feet, and containing 
large crystals of white felspar and small crystals of graphite. Half-way down the 
mountain below this are some loose blocks of “ Stangel Gneiss,” outwardly bearing 
a resemblance to stems of fossil trees. 
Towards the point at the head of Mogok valley, where the Yenee river emerges 
from the limestone, the red loam rests upon the semi-decomposed gneiss, with huge 
rounded blocks of the latter rock on the surface ; the hills thus formed close in on both 
sides of the river, constituting a barrier, which separates the level bottom of the valley 
from a second extensive flat alluvial area, extending up to the head of the river. 
Two-thirds of a mile southward of Mogok, in the narrow gorge of the Mogokchoung, 
is an exposure 300 yards in width, of dark-coloured, fine-textured gneiss in vertical 
bands, varying from a foot or two in width to 10 feet. Interfoliated with these are 
two layers of crystalline limestone, the first being 30 feet wide, in which is a band 
of gneiss one foot in width ; and in the second, which is 20 feet wide, are several 
narrow vertical bands of dark-coloured, fine-textured gneiss. There are also bands 
of pegmatite in the gneiss, one of which is five feet in thickness. From this section, 
laid bare by the river, showing the limestone, when it is not visible along the range 
either east or west, owing to the covering of hill-wash, it must be inferred that 
in many other places there are small bands of crystalline limestone in the gneiss, 
which are not seen at the surface on the hill-sides. It is only the large bands of 
limestone of great thickness, whose outcrops stand out in jagged masses above the 
surrounding surface, that prove the existence of this i^)ck and form an important 
feature in the geology of the district. In the limestone beds above mentioned, are 
violet-coloured crystals of garnet, and the same are also seen as accessories in the 
adjoining gneiss. 
From Mogok valley, on the road to Momeit via Kyaukwa, up to the pass, 
where rock outcrops are visible, they are all of gneiss, thin-bedded and grey, with 
interfoliated coarse, whitish gneiss, and pegmatite containing garnets. At the pass 
itself all the rocks are whitish pegmatite. In a line with the dip of the gneiss on 
the peak close to Letnytaung (Lennu Taung), a flat-lying, grey gneiss is seen on 
this road, which probably is the same as that of 40 feet in thickness which caps the 
crystalline limestone of the peak, and does not coincide with the usual dip, but slants 
irregularly in a south-easterly direction at an angle of 35°. It may be that here 
there has been some disturbance, in the form of a more or less horizontal fault, or 
a “ lateral thrust.” To the east of the pass the mountains of gneiss are extremely 
decomposed to a great depth, and contain a band of pegmatite in which are 
bluish crystals of apatite Near by to the south, this rock contains large crystals of 
