F. Kingdon Ward—The Land of Deep Corrosions. 217 
of narrow gullies on the main spurs, separated by razor-edged walls 
of rock standing out like ribs. The Mekong—Salween divide is here 
capped by granite, with outcrops of grey slate, instead of by limestone. 
Further north are various metamorphic rocks. Altitude 15,000— 
17,000 feet. On the main spurs a succession of broken anticlines 
can sometimes be traced, causing the crests of the spurs, which are 
very steep-sided, to be jagged like a saw. Conglomerate was seen 
in one place at 17,000 feet. 
In the valley of the Wi-ch‘u, which is crossed twice before the 
Salween is reached, limestone and schists, dipping north at high 
angles, are met with. 
In the Salween valley the rocks are mostly limestone and granite 
in the north (i.e. north of Atuntsi), limestone, slates, and schists 
further south. The river cuts its way through remarkable gorges of 
granite and limestone, in some places crystalline, and at one place 
there are conspicuous scarps of the latter rock, like old river gorges, 
a thousand feet or so above the river. 
The summit of the next range to the west, the Salween—lrrawaddy 
divide, I have not yet crossed in this latitude, though I have several 
times seen its snowy peaks; but a hundred miles further south the 
great bulk of itis granite, with conspicuous cliffs and peaks of limestone 
cropping out lower down on the Burma side, and the same vertical 
slates reappearing in the bed of the ’Nmai-hka at least as far north 
as latitude 27°; still further north it appears to flow, like the 
Salween, through granite gorges. 
Leaving the ’Nmai valley and continuing westwards to Hkamti- 
Loong (latitude 27°), we pass from the igneous rocks of the great 
mountain ranges to laterite and clays as the plain is approached, and 
finally to sands and alluvium on the plain itself, overlying a hard 
conglomerate which contains rolled pebbles of many igneous rocks. 
The plain is divided by three conglomerate! terraces of varying 
breadth, rising one above the other from the river and trending in 
a more or jess north and south direction; they appear to be old river 
terraces, but their discussion is irrelevant here. 
Southwards of Hkamti-Loong we find in sequence fia north to 
south the following: (1) Gravel interstratified with sand, often iron- 
stained and showing current bedding; in places converted into 
conglomerate by the “weight of superincumbent rock and the infiltra- 
tion of water carrying iron salts in solution. (This is well seen in 
a nulla, the ‘conglomerate nulla’, three marches south of Hkamti.) 
I will digress here for a moment to comment on these interstratified 
sands and gravels. One cannot look at the upper Mekong in summer, 
its red flood hurrying along sticks and branches, and at the same 
river in mid-winter, its shrunken waters blue as the Mediterranean, 
without perceiving that a river which is largely fed by glaciers and 
melting snow, or one which flows through a region with marked dry 
and rainy seasons, may lay down strata of two distinct ty pes. Summer 
and winter deposits may in such case be as sharply demarcated as the 
? The conglomerate is not solid right through, but forms an irregular ‘ pan’ 
at varying depths. 
