In Troubadour-Land: A Ramble in Provence and Languedoc

by S. Baring-Gould

The inclination of the bed of the Rhone between Tarascon and Arles is four feet three inches in the mile; but at Arles the elevation of the bank is but three feet six inches above the level of the sea; and the river has to run sixty-two miles before it reaches salt waves. Consequently the bed widens, the river branches, and the rapidity of its movement diminishes progressively. The alluvium is deposited, banks multiply, the mouths are encumbered with submarine islets, locally called theys, which the waves and currents of the sea displace and remodel continuously, and render the entrance to the river impracticable. [1]

[Footnote 1: Lenthéric: 'Les Villes Mortes du Golfe de Lyon,' Paris, 1883.]

River mouths vary greatly; they are either estuaries, like those of the Thames, the Seine, and the S. Lawrence, or they are deltas, like those of the Nile, the Po, and the Rhone. Very generally in tidal seas we have estuaries; but in those that are tideless, as the Mediterranean and the Black Sea, they are deltas. Where there is a tide, the mouth of the river is washed out and kept open by the flux and reflux of the sea; but where there is no tide there is nothing to interfere with the river choking its mouth with its deposits. In such a case, after a while, the mass of deposit becomes so great as to interfere with the course of the river. The sea beating against this bar throws up sand and gravel upon it, and at every storm raises it higher. Then the river divides into two or more branches, and forms for itself new beds, which are destined in turn to undergo the same process.

Now, when a river has formed its bar choking its mouth, and is then forced to make a fresh mouth, it leaves a lagoon behind this bar. At every flood its waters overflow, and are unable to escape to the sea when left behind the bar. Sometimes, in like manner, in a gale of wind on shore, the waves are carried over the bar, and there are left as a brackish pool, unable to return to the sea.

Thus the whole of the Bay of the Gulf of Lyons is masked by a false coastline of old bars, behind which lie lagoons all formed in the way indicated. Between Rousillon and Leucate is the Etang de Salses; Narbonne anciently was seated in the lap of another great inland lake or lagoon. The vast Etang de Tau has a barrier between it and the sea on which is planted Cette. Lagoons behind bars extend thence the whole way to Aiguesmortes; and between the mouths of the Rhone, as they flow at present, is the Etang de Valcarès.

After the river has deserted its old bed, and the lagoon has been formed behind the bar, or littoral cord, wave and storm working upon this long line of mud and sand succeed in breaking through; then, as the inclination of the land is but 0'm, 01 in the metre—almost nothing, the sweet and salt water mingle in these lakes, they never run dry, though in many cases not three feet deep.

A look at the map of the Gulf of Lyons will show the reader that its special characteristic is the chain of lagoons separated from the sea by a narrow ribbon of sand. It may have caused perplexity in the mind of many that the Gulf should bear the name it does. It cannot take its name from the city of Lyons—the ancient Lugdunum—which is two hundred and twenty miles inland. It certainly cannot derive it from the wild beasts—lions—for there are none nearer than Africa.

The fact is, that the Gulf takes its title from the Keltic word for a lagoon, lôn or lyn, a name that recurs in Maguelonne—the Dwelling on the Pool—in the Canal des Lonnes, a channel connecting the ponds and lagoons of the Durance and Rhone, and, indeed, in our own London (Londinium) the Dinas, Castle on the Lon, or pool of the Thames and the Essex marshes.

Anciently, in historic times, Arles, that lies near the apex of the triangle formed by the branches of the Rhone, was bathed on one side by the river, by which she received merchandise from the north; and, on the other side by the lones, or submerged land, that extended to the sea; and after Marius had connected these lones with his canal, she exported and imported merchandise over the Mediterranean through the lagoons, as the sea could not be reached by the river on account of its bars.

Moreover, the Greek and Roman cities along the coast are not found on the actual coast, on the bars, but were planted on the lagoons, which afforded them perfect harbourage for their merchant vessels. These lagoons, through which flowed salt and fresh water, were always healthy, and remained healthy as long as communication was maintained with the sea and the river. But wind and wave and alluvium working together choke these communications, and directly the mouth seawards of a lagoon is closed it is converted into a stagnating marsh that exhales malaria.