In that piece of marble alone you have a pretty full review of the earth's history; of many of the most important things we have seen and heard about since we all started out together in Chapter I. It tells of strange life in ancient seas; of being buried deep in the earth under immense pressure, and where it could feel the intense heat of the rock at the centre, and of coming up again completely changed; transformed from the substance of a dead sea creature's shell to a crystallized stone beautifully colored and of many patterns; of the chemistry of the world underground and the laboratories in which its lovely coloring were made and blended; and solid rock threaded through rock with a skill that no worker in mosaic has ever equalled; drawn out and fixed in mere films of white, fading into the rich dark of the marble around them like white clouds shredded by the winds. [Illustration: THE STRANGE STORIES THAT MARBLE TELLS] Those broader lines bending and turning, rising and falling, tell of the work of the giant forces that lift the mountains into place and of the great earthquakes that accompany mountain building. When those little quavering lines were being made, away down in the earth where the limestone changed to marble, mountains were slowly rising into the sky on the earth's surface far above. The quaverings in the marble are pictures, "line drawings" of the mountain story. And beside these lines that you can read so plainly there are others so small that you need a magnifying glass to see them; echoes, away down in the fairyland of the microscope, of the doings of the giants of Mountainland far above. In following the lines of the earth's great walls of rock over a wide extent they are found waving sharply up and down in one section, rising and falling like ocean swells in another, in forward sloping folds in another, and sometimes even with folds doubling over, as if the great mountains which these folds made were trying to stand on their heads. WHY LINES IN MARBLE REPEAT MOUNTAIN FORMS All these rock folds which, with the help of the sculpturing of the elements, produce the infinite variety of beauty in mountain scenery are, speaking generally, repeated in the lines of the marble. But they are repeated only in miniature, because the rocks deep in the earth are under such pressure that while the rocks on the surface are free to rise in big and comparatively simple waves those beneath are doubled up into smaller and much more crumpled folds. Take several sheets of paper lying free on the table and press them from the ends. They will rise in simple arches as most mountains do. Now lay a book on these sheets and press from the ends again. You see they crumple up a great deal more; the larger wrinkles themselves doubling into smaller ones. [Illustration: HOW MOTHER NATURE MAKES HER Z'S