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SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
Fig. 3. The Nari detachment line 
The process of Nari disintegration starts at the base of the mountain slopes 
near the main tributary (fig. la), being initiated by undercutting of this slope 
base by the floodwaters of the main tributary. As a consequence the Nari is 
eroded, and the soft chalk revealed. Later on, blocks of Nari are detached from 
the slope above and creep slowly downslope. A low cliff (about 2-3 m) is 
found on the line of the Nari detachment (fig. 3) for which the name Nari line, 
or Nari detachment line, is suggested by the author. The process continues 
slowly upslope (fig. lb) until the soft rock, and the calcareous soil associated 
with it, are exposed along the entire slope. 
The disintegration process is accelerated by the aid of small tributary gullies 
which cut upwards into the soft rock from the main tributary. As a result small 
depressions are formed (fig. lc, d, fig. 2a) which are bordered on three sides by 
the Nari line. As the process continues, these depressions widen and occasionally 
merge, leaving islands of Nari at the lower part of the slope (fig. 2b). Ultimately 
all the Nari disappears, but this final stage has been reached in a few places only. 
The Nari disintegration is much faster on the southern slopes than on the 
northern ones. It seems that the dense vegetation on the northern slopes 
retards disintegration by decreasing erosion [cf. figs. 4 and 5). 
The features of the Nari slope are quite different from those of the chalky 
slope. Most, or even all of the Nari slope is convex; if present at all, the con 
cave part is restricted to the slope base. This slope generally lacks scree and 
only occasionally on the steepest slopes may there be found insignificant 
amounts of scree. On the other hand, the slope where the Nari has been