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.
HOW MOTHER NATURE MAKES HER Z'S
These Z-shaped rock folds were made by the crumpling up of the crust as the centre, cooling, shrank away. They are to be seen near the east end of Ogden Canyon, Utah. The black lines were added to the photograph in the offices of Uncle Sam's big department of geology at Washington, to show clearly just where the rock runs.
You may often have noticed a banded effect in marble. My, what power it took to do that! Pressure we can't realize. Pressure from above so great that it made this marble spread; moulded it like clay in the hands of the potter; the same kind of force that flattened out the pebbles referred to in [Chagter V]. This is called "rock flow," and how plainly the marble shows the flowing movement. I always think what the weather people call "stratus" clouds, look as if they were made by long strokes of a painter's brush; and this marble has the very same flowing lines. Such cloud pictures in marble are made where deposits of other kinds of rock have been interlaid with the deposits of limestone which afterward changed to marble, and it is where these bands are folded or bent that we have set down for us the story of the mountain folds.
Those gossamer effects and the little white clouds spinning out and fading into the general mass of the marble, how delicate they are! Yet it took a force that made the earth quake to put them there. The more we know of the strange and fearful things that happen in times of earthquake the more we can read between these filmy lines. They tell of the sides of mountains tumbling down and spreading their valleys with a chaos of broken stone; making cliffs where there were peaks and peaks where there were cliffs; changing the course of rivers; shifting whole forests on the mountainside and replacing them with grim walls and bastions of barren stone—all in the twinkling of an eye!