F. Kingdon Ward—The Land of Deep Corrosions. 2138 
the north and south trending parallel ranges which lie between 
Assam and Western China, though the Himalayas may have and 
probably did receive their last and greatest uplift (in Tertiary times) 
at a subsequent date. 
During the period of the first phase the region we are considering 
may have appeared somewhat as follows: (1) The Himalayas, 
either continuous with, or at least throwing out spurs to, the main 
divide of China (a consideration of the distribution of plants on the 
Himalayas and in Western China leads to this conclusion). (2) A great 
lake or system of lakes stretching throughout the present headwaters 
of the Mali-hka westwards into Assam, and covering thousands of 
square miles. (3) A region of great lakes and volcanic activity in 
Western China. (4) A number of rivers flowing into these rivers 
from the west, of which the upper courses of the Brahmapootra and 
Salween may have existed more or less as at present, eventually 
becoming involved with rivers consequent upon the second phase. 
At this time the Irrawaddy can have had no existence, nor probably 
had the Mekong. The Yangtze, however, flowed eastwards from the 
neighbourhood of the Chengtu plain, then a vast lake; its present 
upper course (distinguished as the Chin-sha-chiang) did not exist, 
and the same applies to the lower course of the Salween. 
The second great phase now seems to have been initiated by a crust 
movement from west to east, accompanied by the irruption of vast 
masses of granite. It may be thata lateral shifting of the Himalayan 
axis eastwards accounted for this, or perhaps it was due to a natural 
shrinking and settling of the crust; but whatever the cause, the 
parallel ranges to the east were those first formed, the western ones 
being pushed up later (the glacial phenomena and the distribution of 
flora on the parallel divides show this). 
The result of this second earth movement was to break the 
continuity of the Sino-Himalayan axis, and start rivers flowing 
southwards through the breach. Thus arose the Mekong and the 
lower course of the Salween from about latitude 29°, while the 
draining of the Hkamti-Assam country gave rise to the Irrawaddy. 
At this time too the Chin-sha may have flowed southwards past 
Talifu to the sea through Indo-China. The parallel divides were 
then much lower than at present, and the monsoon rains swept on 
into Western China, where there were great glaciers. Meanwhile 
the rivers of the old system were rapidly cutting back, with the 
result that the Yangtze eventually tapped the Chin- sha, while 
the lower and upper courses of the Brahmapootra, cutting down as 
the Himalayas rose, became united. All this time the parallel divides 
were being slowly elevated, gradually pushed up one by one from the 
west, but the probability is that they had attained no great elevation 
till the present hydrographic system was established, and there is 
reason to believe, from a consideration of the glacial phenomena on 
the Mekong-Yang gtze and Mekong—Salween Tease matter which 
requires separate treatment—that they are still rising. 
I have stated my belief that the parallel divides, with their 
intervening valleys, were formed by pressure from the west—that is 
to say, that the region is a series of anticlines and synclines; and on 
