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0715 Southern Tibet : vol.7
Southern Tibet : vol.7 / Page 715 (Grayscale High Resolution Image)

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doi: 10.20676/00000263
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The erosion of a river works up-stream from the mouth to the source, and
its ultimate goal is to give the riverbed the profile of a parabola. The erosive
action is at its maximum where the slope is steepest. The Drugub river has a
considerable erosive power which would increase during a moist period. It cuts
down its bed in the direction of the Panggong threshold, and will finally cut through
it, thus again capturing the Panggong Lakes and transforming them into a river.
The ultimate goal of this action is to give the Tso-nyak — threshold — Drugub line
in the upper profile of our diagram, the same appearance as the Hlagar—Demchok—
Lungkung line in the lower profile. Lakes of the Panggong type are therefore very
ephemeric phenomena on the earth.