The ancient Bronze-age community on its northwestern shore, Orchomenos, is now a modern city at the edge of the farmland.

The limestone beds of which the mountains of Greece are mainly composed were deposited at the bottom of Neotethys Sea.

So far the only evidence of glaciers in Greece are the cirque features of the Pindus Mountains, of which Parnassus, a purely limestine peak, is an offshoot.

Moreover, if there had been any extensive, repeated flooding, the three land bridges would have eroded away, and the Cephissus would be left at the bottom of a river valley emptying into the Gulf of Euboea.

The large amount of flood waters formerly stored by Copais could no longer collect there but must be passed on to Yliki and Paralimni.

The elevation of the surface of Yliki having been at 45 metres (148 ft) now rose to 70 metres (230 ft), average figures, with a concomitant increase of surface area from 13 square kilometres (5.0 sq mi) to 22 square kilometres (8.5 sq mi).

A 3 kilometres (1.9 mi) canal was planned between Lake Yliki and Paralimni, the Mouriki Channel, and was excavated down to an elevation of 78 metres (256 ft).

The realization that even in flood the lake level would never rise to that elevation stopped work on the channel, which is visible as a controlled waterway on the Yliki side but in fact dries out further on and does not go through to Paralimni.

The latter not only erased tracks and roads, and made the land non-arable and unbuildable, but rendered any possible archaeological evidence inaccessible, at least temporarily.

Paralimni, a 10 kilometres (6.2 mi) lake in the NE to SW direction, is locked by mountains for most of its length.

Ptoion, a mountain range on its north shore, which separates it from the Gulf of Euboea, descends to the water's edge in slopes and cliffs, especially since the expansion of surface area.

In a similar case, although not quite as severe, are the foothills of Messapio, which come down to a somewhat lesser length on the south side.

The east end, a flat and fertile area, is approachable from Anthidona, also called Mandraki from its harbor, which is on the Gulf of Euboea.

Archaeological evidence there pushes the earliest date of the site back to the Neolithic; that is, to a pre-Greek era.