Across the China-Tibet Frontier he 
are neither so high nor so steep as in the case of the 
other two’. 
(iii) It has the slowest current of the three, though 
it brings down much more water than either of the others. 
(iv) It flows at a considerably higher level. This is 
a point to which we shall have occasion to refer again. 
(v) Itis interrupted by fewer rapids. From the Batang 
river to below the ferry, a distance of quite twenty miles, 
there is not a single rapid which would impede navigation 
by canoe. 
(vi) A continuous shelf of alluvial detritus and blown 
sand forms a low platform or bank between the river and 
the mountains, so that on either side the path rarely need 
ascend to any height above the river. Small sand-dunes 
are not uncommon. Houses are not, as on the other rivers, 
confined to the mouths of ravines, but occur scattered along 
both banks. 
(vii) There are no gorges, big screes, or spurs pro- 
jecting far out into the river, so that the latter maintains a 
much straighter course, and there are none of those abrupt 
S-shaped curves so typical of the Salween. 
(viii) Some of the tributaries are of considerable size, 
and flow quietly into the Yang-tze from wide valley mouths. 
Nowhere is the basin of this river so narrow as are those 
of the other two. 
Possibly the Yang-tze is nearer its base level of erosion 
than either of the other rivers with which we are comparing 
it, and hence is much older. This at least would be in 
accord with the theory that the watershed between the 
Mekong and Salween rivers was thrown up at a time 
subsequent to the elevation of the Yang-tze-Mekong water- 
shed. In spite of the differences mentioned above, one 
meets with the same rocks in the valley of the Yang-tze as 
in those of the Mekong and Salween—limestone, granite, 
and metamorphic rocks. 
After leaving the coracle we secured porters from the 
village and started for the ferry a few miles down the 
river; meanwhile dusk fell and a stormy night set in, 
heralded by distant thunder. Just as we embarked in 
1 A combination of these two characteristics precludes, as already remarked, 
the possibility of rope bridges over the Yang-tze. 
Q—2 
