Stora Alvaret

Stora Alvaret, Swedish for the Great Alvar, is a barren limestone terrace in the southern half of the island of Öland, Sweden. It is a dagger-shaped expanse almost 40 kilometres long and about 10 kilometres wide at its broad northern end, with an area above 260 square kilometres. That makes it the largest alvar in Europe and more than a quarter of the island's land. The limestone formed about 500 million years ago in more southerly seas, and glacial action from ice age advances shaped the plain. The soil layer is extremely thin, only about two centimetres at its deepest and absent in many places, yet the high pH supports a rich mix of plants, including rare species, stunted sparse trees and a few seasonal wetlands. Linnaeus described its biota in 1741. Stora Alvaret lies within the UNESCO-listed Agricultural Landscape of Southern Öland, recognised for its long prehistory of human settlement.