Let us scoop up a little sand from the sea-shore, and look at it under a magnifying-glass.
We shall find a number of loose yellow grains, not all alike in shape, but all somewhat rounded. Most of them are characterised by a glittering hardness, and probably some are transparent.
For the most part these grains are of a substance called quartz, which may be almost any colour from white to black. Some beautiful forms of it are known to us, such as amethyst, agate, and jasper. But we have now to do with the humbler relatives of those aristocratic gems; with the more commonplace kinds of quartz, such as sandstone.
Sandstone rock is chiefly made of grains of sand, firmly compacted together. An especial interest belongs to the rounded shape of these little grains. Like many voiceless things in the world of inanimate Nature, it tells its own tale, if only we will pause to hear.
Why should grains of sand be rounded? Why not square, or pointed, or angular?
That is just what they were, not very long ago. Each sand-speck, when first detached from rock or stone, had its angles and corners. But these have been gradually rubbed away; and by the very same process which, in the course of years, rubs away angularities and eccentricities from the characters of human beings.
The work has been done through contact with its neighbours—not by an occasional rub, but by steady friction, long continued. Each grain of sand, rubbing against and being rubbed by its companion-grains, has been rounded, smoothed, polished, till it has grown into the finished specimen, without any obtrusive points or disagreeable angles remaining.
An unpleasant discipline, perhaps; yet, in the case of sand-grains and also of human beings, worth undergoing for the sake of results.
Looked upon from a geological point of view, this shape of the sand-grains means merely the wearing and wasting away of substance, with no pretty explanation attached, though with a very definite underlying story of their past history.
“No workman ever manufactured a half-worn article, and the stones were all worn.” So wrote Hugh Miller when describing his first boyish experience of toil in a Scotch quarry twenty years earlier. Boy as he then was, his keen eyes noted the stones, “rounded and water-worn, as if they had been tossed in the sea or in the bed of a river for hundreds of years.” Boy as he was, he knew that stones, broken off from larger stones or rocks, have at first their irregular shapes, their corners and jagged points, which can only be worked into smoothness by the action of water. Boy as he was, he realised that these quarry inland stones had once been rubbed and shaped by ocean-waves.