SOIL FORMATION: ROCK DISINTEGRATION. 3 ! 3 



longer uncovered by ice \vere being covered by plant life. One 

 of the Greenland rock lichens is shown in fig. 262. 



479. Other plants of rocky regions. Certain of the higher 

 plants also find means of attachment to the bare rocks of the 



Fig. 261. 

 Edge of glacier in Greenland, showing freshly deposited rocks. (From Prof. R. S. Tarr.) 



arctic and mountain regions. The roots penetrate into narrow 

 crevices in the rock, and are able to draw on the water which is 

 elevated by capillarity. Such plants, however, which live on 

 bare rocks, whether in the arctic or in mountain regions, have 



