Between Land and Ocean a ceaseless contest is carried on. The land is always endeavouring to keep its present state unchanged. The ocean is ever trying to tear down and demolish the land. Yet the very object of the ocean in so doing seems to be that new land may be raised up with the stolen materials. There are Continents and Islands, moulded long ago, which we see as finished structures, that have reached the meridian of their existence and entered upon their decadence. With many of these Ocean’s efforts are chiefly employed for destruction. Indeed, in all cases, the power which once erected an island or a continent is at work upon it still, not always and only for destruction, but sometimes for modification, altering its shape, making it larger or smaller, rounding a curve here, adding a protuberance there, giving finishing touches, and in the end, if not from the beginning, acting also as spoliator. But the work of building has not ceased; it never does cease. Through the ages it has gone on, and it goes on yet. There are embryo islands, perhaps embryo continents, being now slowly fashioned in Ocean’s workshops, not ready for use. A great part of the work of land-building takes place in darkness. It is carried on, not merely from day to day, but from century to century, never hasting, never pausing. The materials are brought often from far distances, not by men, but by streams, by rivers, by glaciers, by ocean-waters; and the weight of those waters helps to weld the gathered materials into a solid whole. Anybody who watches the results of even one heavy downpour of rain on land may gain some notion of what is going on everywhere. If your house has a soft-water tank, you can hardly have failed to note how black the water becomes, after a pelting shower, following upon a drought. No wonder, for the rain has washed the roof, and has carried off a supply of collected dust and soot. Not the roofs of houses alone, but the streets, the walls, the pavements, in a town--the trees, hedges, grass, roads, in the country--are all relieved of dusty layers, while, if the rain be heavy enough, sand and soil also are swept away. Sometimes they are only taken to a lower level in the same neighbourhood, but large quantities find their way into the drains or streamlets, which join bigger brooks, and thus reach the nearest river, finally joining the sea. Any moving stream is able to carry along floating materials, which in still water would sink to the bottom. The faster the current the heavier is the weight which it can support. A mountain torrent conveys pebbles, grinding them to a smaller size as it rushes along; and some of the more powerful torrents transport even great stones.