THE STORY OF A STRANGE LAND. 259 . 
other times the water came down little by little, 
insinuating itself into many places at once. Then 
the hot rocks threw it back in many little honey- 
comb channels, and by the spreading of these 
channels the rocks were at last crumbled to pieces. 
The hard black lava or the glass-like obsidian were 
changed to white kaolin as soft and powdery as 
chalk. And as the water fought its way, gaining 
a little every year, steadily working between the 
joints in the enemy’s armor and as surely being 
thrown back with violence if it penetrated too far, 
the animals and the plants followed in the wake of 
the water, and took possession of the territory as 
fast as it was won. 
At last the Pliocene times were over, for all 
times come to an end. The one sure thing on the 
earth is the certainty of change. With the change 
of time came on the earth’s great winter. The 
snow-drifts on the lava were piled up mountain- 
high. Snow is but ice in little fragments which 
will grow solid under pressure. As the snow 
accumulated it began to move, forming great 
rivers of ice which ran down the courses of the 
streams. And as these slowly moving, gigantic 
ice-rivers tore away huge blocks of lava and pushed 
them down the mountain-sides, where the rocks 
had been softened by the action of steam, the ice 
wore out deep valleys, and everything that it 
touched was smoothed and polished. The winter 
of the great Ice age lasted a very long time, many 
thousands of years; but, long as it was and long 
ago, it came at last to an end, — not toa full stop, 
of course, for even now some of its snow still 
