But whatever caused it one thing is certain; it was a winter that beat anything the oldest inhabitant ever saw; for the cave men are known to have been on earth during this great winter, which is known as the Ice Age or the Glacial Period. A great big ice cap reached from the North Pole far down into the Temperate Zone in North America, Europe, and Asia. [Illustration: FROM THE CAVEMAN'S DIARY This is a little note on the Ice Age from the caveman's diary--the picture of a mammoth scratched with a flint on a mammoth's tusk. You can see how the artist kept trying for the true form with different lines, as all real artists do. Artists don't just have a kind of sign that stands for the thing--like a little boy's picture of a man that he always makes in just one way. Notice the action, the natural motion of the animal. The artist means to say: "This is the way he came at me." ] I. The Mild Spell and the Menageries Just before this dreadful winter set in we had a long, open spell; about a million years or so. It was just like summer most of the year in the temperate zone, and much warmer than it is to-day in what is now the land of the little frosty Eskimo. There weren't any little Eskimos in those days. In fact, there wasn't much of anything that was little. Everything was on a big scale. Think of a mud-turtle twelve feet long! He was all of that. His skull alone was a yard long and he must have weighed a couple of tons. He had for neighbors in the bordering swamps a number of huge creatures that one wouldn't care to meet. [Illustration: THE KING OF THE DINOSAURS AT LUNCHEON Contrast the little, almost dainty, fore limbs with the enormous legs. You can't help thinking of the arms of a human being, can you? In fact, this mixed-up creature looks as if nature were even then dreaming of man, the quadruped who, as some Frenchman said, "took to walking on his hind legs that he might conquer the world." ] DREADFULNESS OF MR. DINOSAUR The Dinosaur, for instance. His name means "terrible reptile." Some members of the family were, indeed, terrible creatures. Just see this one at lunch, Mr. Ceratosaurus. He has the head of a queer horse--"probably a night mare," says the High School Boy--teeth and tail and belly scales like a crocodile, a comb that suggests a rooster's, legs like an ostrich, the talons of an eagle, and the dainty little arms of a child. What a combination! Those small fore limbs were used only for grasping. On his hind legs he stalked about, seeking whom he might eat for dinner. He was about fifty feet long when he was all there. At this late day scientists usually find only parts of him scattered around.