When the twenty-first century drew to a close the whole human race
began to revert to conditions closely approximating savagery. The
low-lands were unbearable. Thick jungles of rank growth covered the
ground. The air was depressing and enervating. Men could live
there, but it was a sickly, fever-ridden existence. The whole
population of the earth desired the high lands and as the low
country became more unbearable, men forgot their two centuries of
peace. They fought destructively, each for a bit of land where he
might live and breathe. Then men began to die, men who had
persisted in remaining near sea-level. They could not live in the
poisonous air. The danger zone crept up as the earth-fissures
tirelessly poured out their steady streams of foul gas. Soon men
could not live within five hundred feet of sea level. . . .
