LXXIV. The Copaic Lake.—

Like other lakes which are drained not by rivers but by natural subterranean passages in the limestone mountains which surround them, the level of the Copaic Lake varied greatly from time to time. Such variations depend upon two different sets of causes, first the varying capacity of the emissaries, and second the varying amount of water poured into the lake.

In the first place, not only are the emissaries subject to a gradual and regular process of change, their passages being slowly clogged and their mouths choked up by the alluvial deposits which in the course of ages raise the bed of the lake; but they are also exposed to sudden and incalculable changes, wrought by earthquakes, landslips, floating logs, and so on, which may in a few minutes either widen the passages or block them up altogether. In the second place, while these changes, whether gradual or sudden, affect the outflow of the water, others not less marked influence its inflow. For the rainfall, on which the inflow ultimately depends, varies not only with the year but with the season. In the sub-tropical climate of the Mediterranean rain hardly falls in summer, and as a consequence the streams in that season either flow with diminished volume or dry up entirely.

All these various causes combine to produce secular and periodic as well as irregular and unforeseen variations in the level of lakes like the Copaic mere. In no lake, perhaps, have the annual changes been more regular and marked than in the Copaic; for while in winter it was a reedy mere, the haunt of thousands of wild fowl, in summer it was a more or less marshy plain where cattle browsed and crops were sown and reaped. So well recognised were these vicissitudes of the seasons that places on the bank of the lake such as Orchomenus, Lebadea, and Copae had summer roads and winter roads by which they communicated with each other, the winter roads following the sides of the hills, while the summer roads struck across the plain. With the setting in of the heavy autumn rains in November the lake began to rise and reached its greatest depth in February or March, by which time the mouths of the emissaries were completely submerged and betrayed their existence only by swirls on the surface of the mere. Yet even then the lake presented to the eye anything but an unbroken sheet of water. Viewed from a height such as the acropolis of Orchomenus it appeared as an immense fen, of a vivid green colour, stretching away for miles and miles, overgrown with sedge, reeds, and canes, through which the river Cephisus or Melas might be seen sluggishly oozing, while here and there a gleam of sunlit water, especially towards the north-east corner of the mere, directed the eye to what looked like ponds in the vast green swamp. Bare grey mountains rising on the north and east, and the beautiful wooded slopes of Helicon on the south, bounded the fen. In spring the water began to sink. Isolated brown patches, where no reeds grew, were the first to show as islands in the mere; and as the season advanced they expanded more and more till they met. By the middle of summer great stretches, especially in the middle and at the edges, were bare. In the higher parts the fat alluvial soil left by the retiring waters was sown by the peasants and produced crops of corn, rice, and cotton; while the lower parts, overgrown by rank grass and reeds, were grazed by herds of cattle and swine. In the deepest places of all the water often stagnated the whole summer, though there were years when it retreated even from these, leaving behind it only a bog or perhaps a stretch of white clayey soil, perfectly dry, which the summer heat seamed with a network of minute cracks and fissures. By the end of August the greater part of the basin was generally dry, though the water did not reach its lowest point till October. At that time what had lately been a fen was only a great brown expanse, broken here and there by a patch of green marsh, where reeds and other water plants grew. In November the lake began to fill again fast.

Such was the ordinary annual cycle of changes in the Copaic Lake in modern times, and we have no reason to suppose that it was essentially different in antiquity. But at all times the water of the lake has been liable to be raised above or depressed below its customary level by unusually heavy or scanty rainfall in winter or by the accidental clogging or opening of the chasms. As we read in ancient authors of drowned cities on the margin of the lake, so a modern traveller tells of villagers forced to flee before the rising flood, and of vineyards and corn-fields seen under water.

The plan of draining the Copaic Lake, which has been successfully accomplished within the last few years, was conceived and apparently executed at a very remote time in antiquity. Strabo reports a tradition that the whole basin of the lake had at one time been drained and cultivated by the people of Orchomenus, and this tradition has been strikingly confirmed by the recent discovery of a complete and very ancient system of drainage works in the bed of the lake. The discovery was made by the engineers charged with the execution of the modern drainage works. As described by them, the ancient works were composed of an ingenious combination of dykes and canals, which completely encircled the lake and, receiving the waters of the streams which flowed into it on the west and south, conducted them to the chasms on the east and north-east banks. Where the canal skirted closely the precipitous rocky shore of the lake, a single dyke or embankment sufficed, the water being led between the dyke and the shore. But where the canal had to cross a bay, or where the bank of the lake was not high and steep enough to serve as one side of the canal, two parallel dykes were constructed and the water flowed between them. The remains of these ancient drainage works in the bed of the lake are of two sorts. In the first place we see them as low broad mounds, about five feet high and fifty to sixty yards wide, stretching for long distances across the plain, either in an unbroken line or with occasional gaps. Sometimes it is a single mound that we see, sometimes two parallel mounds at a short distance from each other. And between the two parallel mounds or beside the single one a long shallow depression marks the line of the ancient canal. These long, low, broad mounds are clearly the remains of the dykes which formerly enclosed the canals, and which have been gradually reduced to their present level by the ceaseless wash of the waters in the course of ages. In the second place, the line of the ancient canals may be traced by the walls built of great polygonal blocks which in many places support and case the inner side of the dykes. In some places these walls are well preserved, but in others nothing of them remains but a conspicuous line of white stones running for miles through the otherwise stoneless plain.

When the system of drainage by canals which has just been described was in full operation the basin of the Copaic Lake must have been nearly dry. But as we have no ground to suppose that in the historical period of antiquity the lake was ever drained, it would seem that we must refer these ancient drainage works to the prehistoric ages. Now Strabo, as we have seen, has preserved a tradition that the bed of the lake was at one time drained and cultivated by the people of Orchomenus. We shall therefore hardly err in ascribing to the Minyans of Orchomenus—the Dutchmen of antiquity—the extensive system of dykes and canals by which the vast plain was reclaimed from the waters and converted into waving corn-fields and smiling vineyards, which poured wealth into the coffers of the burghers. This was the golden age of Orchomenus, when its riches vied with the treasures of Delphi and the wealth of Egyptian Thebes.