Stora Alvaret

Stora Alvaret (the Great Alvar) is a limestone barren plain on the island of Öland, Sweden. Because of the thin soil mantle and high pH levels, a great assortment of vegetation is found including numerous rare species. Stora Alvaret has been designated as a World Heritage Site by UNESCO due to its extraordinary biodiversity and prehistory. The area of this formation exceeds 260 square kilometres (100 sq mi), making it the largest such expanse in Europe and comprising over one fourth of the land area of the island. Stora Alvaret is not devoid of trees, contrary to a common misconception; in fact, it holds a variety of sparse stunted trees akin to a pygmy forest. Stora Alvaret is a dagger shaped expanse almost 40 kilometres (25 mi) long and about 10 kilometres (6.2 mi) at the widest north end.

Geological origins

The limestone plain was created by glacial action from earlier ice age advances. The limestone formation itself was created about 500 million years ago in more southerly seas. Gradually hardening into limestone and drifting northward, the limestone of Stora Alvaret contains a rich fossil record of some of the marine creatures who contributed to it. For example, orthoceratites are found in some of the present day structures on the island.