Moving south, away from the edge of the European ice sheet, the tundra stretches about halfway down to what used to be France. There, the bleak landscape is gradually replaced by clusters of trees such as rowan and birch. Further south, trees become more abundant and conifers appear. Isolated clusters become unbroken forests of conifers. Where the Alps rise, another band of glaciation occurs - towering mountains of ice creeping slowly down the valleys. Beyond these Alpine glaciers, stretching southwards, lies the Mediterranean Basin.
The Mediterranean Basin is a vast depression in Earth's crust, some 6,500 feet (2,000 meters) below sea level in places. It is now a region of brine lakes and salt flats, surrounded by dry, ridged limestone landforms, called karst. The air is dusty and parched. This is what remains of the gentle beaches, warm waters and hospitable climates of the former Mediterranean Sea. The sea, around which great human civilizations once thrived, has dried up.
During the previous times, the Mediterranean Sea was fed by a constant influx of water from the Atlantic Ocean through the Strait of Gibraltar. As global temperatures dropped, the icecaps expanded, and sea levels fell. The threshold of the Mediterranean became exposed and the flow of water stopped. This, coupled with the slow collision of the African Plate and the European Plate, has left the Mediterranean landlocked.
Despite influxes from rivers flowing from Europe and Africa, the sea gradually evaporated. As the sea level dropped, the concentration of minerals in the remaining water rose, and vast limestone deposits began to form on the floor of the shrinking sea. As the water evaporated further, stretches of limestone pavement became exposed. It took about one million years for most of the sea to evaporate and now, in 5 million AD, any water left has collected in hypersaline lagoons in the low basins.
Out of the brine lakes and fissured limestone karsts of the Mediterranean Basin rise majestic mountains. These are the former holiday islands of Majorca, Crete and Cyprus, among others, that now stand tall and exposed on the harsh, dry plains. Global temperatures are five or six degrees lower than they were in the Quaternary, and nowhere is this difference felt more than in the Mediterranean Basin. This once warm, sundrenched region is now an arid, cold and rocky land.
The salt flats of the Mediterranean Basin shimmer in the cold sunlight. What little water there is lies in the deeper basins, forming scattered, shallow lakes. The waters in these lakes are ten times more salty than seawater. They contain no fish. The only life than can survive in such a hypersaline environment are simple algae and bacteria that feed on the rich chemical soup. At the edges of the salt lakes, large clouds of brine flies gather. These tiny black flies have always flourished under such conditions, and continue to do so now, feasting on the algae and bacteria in the shallows.
The surface of the Mediterranean salt plain is completely flat. On the rare occasions that it rains here, the top surface of the salt is dissolved into a saline mush. As the water evaporates, the surface is once again flattened. The whiteness is only alleviated by the odd smudge of red produced by the salt-loving bacteria.
Around the edge of the salt lagoon, the landscape gradually changes from white to grey. This is the karst - a region of rocky limestone rocks and pinnacles, separated by deep fissures called grykes. Grykes are formed by gradual action of rainwater on natural cracks and faults in the rock. Over time, the water has a weathering effect on the rock, dissolving the limestone and deepening the fault lines into larger fissures until, finally, they become grykes. What soil there is in this dry landscape gathers at the bottom of the grykes, enabling some vegetation to take root. Some grykes stretch down two or three meters, ideal places for reptiles to lay their eggs.
On slightly higher ground, away from the edge of the salt flats, soil particles blown into the grykes from the continental interior allow vegetation to grow. Patches of wispy grass sprout up from the flat surfaces of the clints. Hazel trees grow in bunches along the grykes, stunted and gnarled, their roots reaching down hundreds of feet to whatever water table exists here.
The chasms tend to run at right angles to one another, a legacy of Earth-moving forces that cracked the rocks originally.