NATURE'S MASONRY 



919 



slipped down its face during the progress 

 of Nature sculpturing ; this is carried away 

 by the highest tides, but is constantly 

 being replenished from above by the 

 action of the springs, the wind and rain. 

 Ice is one of Nature's most powerful 

 chisels wherewith she splits the hardest 

 rocks. To see how this work is accom- 

 plished we must visit some high, exposed 

 cliff on the mountain side after a night 

 of frost. Perhaps the previous afternoon 

 the clouds hung low upon the mountain, 

 swathing it in a rolling mantle of grey 

 mist, until every crack and cranny of the 

 rocks was filled with water. As the night 

 drew on, the temperature gradually fell 

 lower and lower, until the moisture-laden 

 rocks became coated with frost, and the 

 rain that had accumulated in the crannies 

 was converted into solid ice. Now these 

 cold, dark hours have passed and the 

 sun is shining gloriously, and as the frost 

 and ice rapidly thaw, we begin to hear 

 the tinkle of water, and ever and anon the 

 sharp sound of falling stones, the chips 

 falling from the work of Nature's chisel. 



To understand clearly how this ice 

 chisel works we must comprehend what 

 happened to the water as it slowly froze 

 and thawed again. Water as it grows 

 colder contracts in bulk until it falls to a 

 temperature of about 4° C. ; on reaching 

 0° C, the freezing point, it passes into the 

 solid state, and at the moment of solidi- 

 fication suddenly expands ; thus 91-75 

 cubic inches of water at 0° C. will pass 

 suddenly into 100 cubic inches of solid 

 ice. We can now better realise the 

 tremendous splitting power of Nature's 

 ice chisel upon the rock. During the 

 night, the water imprisoned in the clefts 

 of the rock, as it froze, suddenly expanded, 

 and by the force of its expansion split 

 out large and small fragments of rock, 

 which, however, did not fall at once, but 

 were held in position by the grip of the 

 ice. Now the sun beats upon the exposed 

 surface of the rocks, causing the ice to 

 melt, and releasing the split masses of 

 rock, which fall down to the base of the 

 cliffs. In their descent these newly 

 detached masses strike against the face 



THE LAYER ABOVE EACH ZONE OF THESE COLUMNS REPRESENTS 

 THE UPPER PORTION OF AN ANCIENT LAVA STREAM. 



