Herds of bison and wild horses grazed on the uplands and the glades resounded far and wide with the notes of tropical birds which settled in swarms upon the tree tops. At night the hunter slept where the chase found him, trembling in the darkness at the roar of the lion or the mighty saber-tooth tiger.
The coming of the ice For thousands of years the life of the hunter went on with little change. He slowly improved his rough stone fist-hatchet, and he probably learned to make additional implements of wood, but of these last we know nothing. Then he began to notice that the air of his forest home was losing its tropical warmth. Geologists have not yet found out why, but as the centuries passed, the ice which all the year round still overlies the region of the North Pole and the summits of the Alps began to descend. The northern ice crept further and further southward until it covered England as far south as the Thames. The glaciers of the Alps pushed down the Rhone valley as far as the spot where the city of Lyons now stands. On our own continent of North America the southern edge of the ice is marked by lines of bowlders carried and left there by the ice. Such lines of bowlders are found, for example, as far south as Long Island and westward along the valleys of the Ohio and the Missouri.[1] The hunter saw the glittering blue masses of ice with their crown of snow, pushing through the green of his forest abode and crushing down vast trees in many a sheltered glen or favorite hunting ground. Gradually these savage men of early Europe were forced to accustom themselves to a cold climate, but many of the animals familiar to the hunter retreated to the warmer south, never to return.
- ↑ Geologists have now shown that the ice advanced southward and retreated to the north again, no less than four times. Following each advance of the ice a warm interval caused its retreat. There were four warm intervals, and we are now living in the fourth. The evidence now indicates that man began to make stone implements in the third warm interval. The last advance of the ice therefore took place between us and them. It is perhaps some thirty thousand years ago that the ice began to come south for the last time.
