1915-16.] BOTANICAL SOCIETY OF EDINBURGH 35 



stances. There might at the same time be a slewing round 

 of these secondary ridges while they were being pushed up, 

 or they might from the very first lie rather obliquely t6 the 

 primary uplift, owing to the pressure acting obliquely as in 

 the diagrams (the Himalayas trend not due east, but about 

 E.S.E.); and they might be pushed up over the broken end 

 of the primary uplift, thus accounting for that apparent 

 westward tilt to which I have drawn attention. Suppos- 

 ing that the irruption area ^ now sagged back, owing to the 

 pressure being released and the dragging weight of the 

 anticlines, the eastern half of the broken uplift might be 

 isolated ; while, owing to the oblique direction in which 

 the force is acting (from the W.N.W.), the parallel ridges 

 would lie south rather than north of the gap, and would 

 remain in contact with the western half of the primary 



uplift. These changes are illustrated in the following series 

 of diagrams, seen in plan. 



In (i) we see the effect of continued pressure in the 

 formation of the ridge CD between the broken ends C C 

 of the main uplift AB (see diagram (vi) previously). In 

 (ii) the number of parallel ridges has been increased to 

 three, and they have been pushed up over the broken ends 

 of the eastern half of the original uplift AB, In (iii) the 

 new ridges have sagged back, remaining in contact with the 

 western half of the uplift, and isolating the eastern half. 



Now the result illustrated in (iii) seems to me very much 

 the condition of the country under discussion at the present 

 day, the Himalayas being represented by AC, the parallel 

 divides (in the limited sense, that is, the Salween-Irrawaddy, 

 Mekong-Salween, and Mekong- Yangtze divides) by CD, 

 and the backbone of China, the great divide stretching 

 across the country between the Yangtze and Yellow rivers, 



1 By this term I mean the whole country of parallel ridges from the 

 Brahmaputra in the west to beyond the Yangtze in the east. 



