How different is the aspect of these shores along which the ever-restless sea continually rises or falls! Here steep rock-walls tower up from the deep, while there a low sandy beach extends its flat profile as far as the eye can reach. While some coasts are scorched by the vertical sunbeam, others are perpetually blocked up with ice. Here the safe harbour bids welcome to the weather-beaten sailor, the lighthouse greets him from afar with friendly ray; the experienced pilot hastens to guide him to the port, and all along the smiling margin of the land rise the peaceful dwellings of civilised man. There, on the contrary, the roaring breakers burst upon the shore of some dreary wilderness, the domain of the savage or the brute. What a wonderful variety of scenes unrolls itself before our fancy as it roams along the coasts of ocean from zone to zone! what changes, as it wanders from the palm-girt coral island of the tropical seas to the melancholy strands where, verging towards the poles, all vegetable life expires! and how magnificently grand does the idea of ocean swell out in our imagination, when we consider that its various shores witness at one and the same time the rising and the setting of the sun, the darkness of night and the full blaze of day, the rigour of winter and the smiling cheerfulness of spring!
The different formation of sea-coasts has necessarily a great influence on commercial intercourse. Bold mural coasts, rising precipitously from the deep sea, generally possess the best harbours. Rocky shores also afford many good ports, but most frequently only for smaller vessels, and of difficult access, on account of the many isolated cliffs and reefs which characterise this species of coast formation.
In places where high lands reach down to the coast, the immediate depth of the sea is proportionably great; but wherever the surface rises gently landwards, the sea-bed continues with a corresponding slope downwards. On these flat coasts the tides roll over a sandy or shingly beach; and here the aid of human industry is frequently required to create artificial ports, or to prevent those already existing from being choked with sand.
On many flat coasts the drift-sand has raised _dunes_, wearying the eye by their monotonous uniformity; on others, where these natural bulwarks are wanting, artificial embankments, or dykes protect the lowlands against the encroachments of the sea, or else the latter forms vast salt-marshes and lagunes. On some coasts these submerged or half-drowned lands have been transformed by the industry of man into fertile meadows and fields, of which the Dutch Netherlands afford the most celebrated example; while in other countries, such as Egypt, large tracts of land once cultivated have been lost to the sea, in consequence of long misrule and tyranny.