CUTTRISS : NOTES ON THE CAVES OF YORKSHIRE. 315 
falls in and a rugged gorge is formed which atmospheric agencies 
may ultimately convert into an open valley. 
As the water trickles down the subterranean cavities partial 
evaporation takes place, when the conditions are favourable, a 
portion of the carbonic acid gas is liberated, and solid carbonate 
of lime deposited. Inequalities in the roof or walls tend to lead the 
trickling water to definite points, where it drops off ; the calcareous 
deposits at these places gradually increase in size and stalactites are 
formed, often of excjuisite beauty and delicacy of form. Usually 
the deeper the cavern from the surface of the ground the purer the 
stalactites. Where the drops of water touch the floor, further 
deposits take place, which continue to grow upwards as stalagmites. 
Given a suflicient lapse of time, both stalactite and stalagmite unite, 
forming a solid pillar, sometimes of astonishing dimensions, and 
these may be fringed round with smaller growths. Again, the walls 
and floors of passages may be entirely coated with a smooth semi- 
transparent calcareous deposit, having the appearance of ice, and 
the deception in places is so perfect that one constantly anticipates a 
fall when walking on it. After a stream has flowed along a passage 
for some time, it frequently finds a lower level, the old course is 
deserted, and a new one formed. In these dry passages the deposi- 
tion of lime is more rapid, and it is in the darkness and solitude of 
such lonely recesses the explorer finds most of beauty, a charm 
intensified by the novelty and weirdness of his surroundings. 
Good examples of the more purely chemical action of water on 
limestone are found in the terraces and exposed surfaces of the rock 
on Ingleborough and the neighbouring heights, especially Moughton 
Fell, the combined areas of which cover many square miles of surface. 
The smooth surface of the rock, laid bare on the retreat of the ice 
during the decadence of the Glacial epoch, or having only a thin 
covering of drift, was exposed to the direct action of the water, 
which opened out the cracks in all directions, completely honey- 
combing the surface. The fissures thus formed are many feet deep, 
while the remaining ribs of rock are rounded and rotten on the top, 
making walking over them very tedious and even dangerous in fog 
or when covered with snow. The combined chemical and mechanical 
