PHYSICAL FEATURES. 
the Lhonak range for many miles beyond the snouts of the present 
glaciers : these deposits have been deeply eroded by the existing 
streams, which have cut out impassable gorges with vertical sides 
often as much as 300 feet and more in depth. 
Similarly from Pauhunri, Chomolhari and the Lingshi range, old 
moraines spread out into the Tiina plain, and show that the 
small glaciers on the northern sides of these mountains are but the 
shrunken relics of what must once have been a great ice-sheet almost 
completely covering the slopes of the culminating range o the 
Himalaya and extending far into the neighbouring plains and valleys. 
A good example of this can be seen in the upper valley of the Nyang 
Chu at Mangtsa, where the bottom and sides of the valley, as well 
as the plain to the south, are covered with a thick mantle of clay 
and boulders deposited by the retreating glaciers. These deposits, 
composed chiefly of granite and limestone brought from the Lingshi 
range, have now been cut by the river into a series of terraces of which 
as many as five or six can be seen on the right side of the valley, 
5. Hot Springs. 
The hot springs of the Lachung valley were described more than 
half a century ago by Sir Joseph Hooker, who found them to have 
temperatures varying from 110° to 116°. Very similar, but appa- 
rently more extensive, springs occur some miles further to the east, 
in the Khongbu valley at about one mile above the village of Yoja. 
The water, which issues from joints in the granite, is distinctly 
sulphurous and its tem.perature is probably about the same as that of 
the Lachung springs. ^ There are altogether thirteen springs, 
several of which are used as baths ; these are greatly frequented for 
medicinal purposes by both Tibetans and Chinese, chiefly for the 
cure of skin diseases and rheumatism, but each bath is supposed 
to have properties not possessed by the others and to be specially 
• Unfortunately my thermometer had been broken and I was unable to verify 
this. 
( ^ 
