The Chautauquan, Vol. 04, January 1884 / A Monthly Magazine Devoted to the Promotion of True Culture. / Organ of the Chautauqua Literary and Scientific Circle.

by Chautauqua Literary and Scientific Circle; Chautauqua Institution

When waves roll in on the land, they break one after another upon the shore, as your ripples break upon the side of the basin. And they continue to roll in after the wind has fallen, in the same way that the ripples in the basin will go on curling for a little after you have ceased to blow. The surface of the sea, like that of water generally, is very sensitive. If it is thrown into undulations, it does not become motionless the moment the cause of disturbance has passed away, but continues moving in the same way, but in a gradually lessening degree, until it comes to rest.

The restlessness of the surface of the sea becomes in this way a reflection of the restlessness of the air. It is the constant moving to and fro of currents of air, either gentle or violent, which roughens the sea with waves. When the air for a time is calm above, the sea sleeps peacefully below; when the sky darkens, and a tempest bursts forth, the sea is lashed into waves, which roll in and break with enormous force upon the land.

You have heard, perhaps you have even seen, something of the destruction which is worked by the waves of the sea. Every year piers and sea walls are broken down, pieces of the coast are washed away, and the shores are strewn with the wreck of ships. So that, beside all the waste which the surface of the land undergoes from rain, and frost, and streams, there is another form of destruction going on along the coast-line.

On some parts of the coast-line of the east of England, where the rock is easily worn away, the sea advances on the land at a rate of two or three feet every year. Towns and villages which existed a few centuries ago, have one by one disappeared, and their sites are now a long way out under the restless waters of the North Sea. On the west coast of Ireland and Scotland, however, where the rocks are usually hard and resisting, the rate of waste has been comparatively small.

It would be worth your while the first time you happen to be at the coast, to ascertain what means the sea takes to waste the land. This you can easily do by watching what happens on a rocky beach. Get to some sandy or gravelly part of the beach, over which the waves are breaking, and keep your eye on the water when it runs back after a wave has burst. You see all the grains of gravel and sand hurrying down the slope with the water; and if the gravel happens to be coarse, it makes a harsh grating noise as its stones rub against each other—a noise sometimes loud enough to be heard miles away. As the next wave comes curling along, you will mark that the sand and gravel, after slackening their downward pace, are caught up by the bottom of the advancing wave and dragged up the beach again, only to be hurried down once more as the water retires to allow another wave to do the same work.

By this continual up and down movement of the water, the sand and stones on the beach are kept grinding against each other, as in a mill. Consequently they are worn away. The stones become smaller, until they pass into mere sand, and the sand, growing finer, is swept away out to sea and laid down at the bottom.

But not only the loose materials on the shore suffer in this way an incessant wear and tear, the solid rocks underneath, wherever they come to the surface, are ground down in the same process. When the waves dash against a cliff they hurl the loose stones forward, and batter the rocks with them. Here and there in some softer part, as in some crevice of the cliff, these stones gather together, and when the sea runs high they are kept whirling and grinding at the base of the cliff till, in the end, a cave is actually bored by the sea in the solid rock, very much in the same way as holes are bored by a river in the bed of its channel. The stones of course are ground to sand in the process, but their place is supplied by others swept up by the waves. If you enter one of these sea-caves when the water is low, you will see how smoothed and polished its sides and roof are, and how well rounded and worn are the stones lying on its floor.

So far as we know, the bottom of the sea is very much like the surface of the land. It has heights and hollows, lines of valleys and ranges of hills. We can not see down to the bottom where the water is very deep, but we can let down a long line with a weight tied to the end of it, and find out both how deep the water is, and what is the nature of the bottom, whether rock or gravel, sand, mud, or shells. This measuring of the depths of the water is called sounding, and the weight at the end of the line goes by the name of the sounding-lead.

Soundings have been made over many parts of the sea, and something is now known about its bottom, though much still remains to be discovered. The Atlantic Ocean is the best known. In sounding it, before laying down the telegraphic cable which stretches across under the sea from this country to America, a depth of 14,500 feet, or two miles and three-quarters, was reached. But between the Azores and the Bermudas a sounding has been obtained of seven miles and a half. If you could lift up the Himalaya mountains, which are the highest on the globe, reaching a height of 29,000 feet above the sea, and set them down in the deepest part of the Atlantic, they would not only sink out of sight, but their tops would actually be about two miles below the surface.

A great part of the wide sea must be one or two miles deep. But it is not all so deep as that, for even in mid-ocean some parts of its bottom rise up to the surface and form islands. As a rule it deepens in tracts furthest from land, and shallows toward the land. Hence those parts of the sea which run in among islands and promontories are, for the most part, comparatively shallow.