The Land of Deep Corrosions 259 
most fundamental necessity would be to show that our 
parallel ridges were of post-Tertiary age, since the Himalaya 
were uplifted during Tertiary times; but it is impossible to 
determine what earth-movements have taken place in a 
country of which not even the roughest geological maps 
are available. Nevertheless, such an hypothesis may not be 
altogether useless even when based simply on impressions 
derived from looking broadly at the country from several 
points of view. 
I do not believe that the region of the parallel rivers 
simply represents a line of weakness along which the waters 
of the Tibetan plateau have found a convenient outlet in 
this direction. Terrific as is the amount of spadework which 
they have undoubtedly performed, I doubt if the life of 
any single river is sufficiently long for the performance of 
such a prodigious task. There are, in fact, reasons for 
believing that such a piece of work was never accomplished, 
and more reasons for thinking that dynamic forces, whether 
in the form of the lateral motion suggested, or as direct 
forces of upheaval, have been at work. 
The rocks show plainly enough that the entire region 
has been pounded in every direction, and though the 
symptoms of volcanic activity are those associated with 
the final phases of vulcanism, not such as are typical of 
its inception, they yet remain to tell the story of probable 
cataclysms in the past. 
Hot springs are to be found issuing from the bases of 
every range. I have seen them in the valleys of the 
Yang-tze, Mekong, and Salween, further south in the valley 
of the Shweli, and continuing westwards, within the basin 
of the Irrawaddy. Perceptible earthquake shocks occur 
from time to time at A-tun-tsi and Batang, and no doubt 
a seismograph would be continually recording slight tremors; 
the numerous landslips which take place in the A-tun-tsi 
district, for instance, suggest a certain amount of instability 
not wholly to be accounted for by the heavy rains. 
A little to the north of T‘eng-yueh, on the low water- 
shed between the Irrawaddy and Shweli river-systems, an 
ancient volcano stands sentinel over the remnants of its 
lava beds, which have flowed down beyond T‘eng-yueh 
on the one hand and across the Shweli valley on the other. 
17—2 
