Rock Expansion by Temjjeratitre Varidtion 23- 



right through (vertically and horizontally) across the centre, and 

 the portion on one side of the crack has sunk one half of an inch 

 to an inch below the other portion. 



This slab of rock has, therefore, been bent and raised to a 

 maximum height of seven inches above the solid rock below; and 

 its bending power was so great that it attained this height before 

 breaking. Temperature variation appears to be the only cause 

 of this phenomenon. 



Tlie accompanying photograph (Plate II., Fig. 2), illustrates the 

 features here described. 



