Mr. Watt’s Observations 
306 
If this idea be not considered as entirely divested of plausibi- 
lity, I may venture to extend the same principle, to account for 
the wonderful regularity of the prismatic configuration of ba- 
saltic columns, and also for their articulations. If we suppose 
that a mass of fluid basalt has filled a valley to an indefinite 
depth and extent, the process of arrangement in its particles 
must be induced by the removal of its heat or moisture, accord- 
ing as its solution is igneous or aqueous. This can only be 
done by the action of the atmosphere on its upper surface, and 
by the ground on which it reposes absorbing the heat or 
moisture from its under surface. From the variations of the 
atmosphere, its action must be irregular; and, from the per- 
petual change of the parts in contact with the heated or moist 
surface, its operations will always be nearly as active as at first, 
allowance being made for its variations. But the absorption of 
the ground will be regular, and regularly diminishing in activity, 
in proportion as the parts near the mass approach nearer to the 
same temperature, or same moisture, with the mass above ; and 
its absorptions can only be carried on by its transmission of 
heat or moisture to the solid rocks below. From these consi- 
derations it seems evident, that the arrangement of the part of 
the basalt near the ground, will be begun with more energy 
than it can be continued, and that the results will be more slow 
and regular than the arrangement induced by the perpetual 
though variable action of the atmosphere. After the first stage 
in the process of arrangement has been performed, and a stra- 
tum, if l may so term it, of the jaspideous substance extended 
over the surface of the ground, there seems no reason to doubt 
so many substances, that Werner has called the formation it seems to indicate; 
“ abgesonderie siiicke,” which has been rendered in English distinct concretions, 
