Caspian Sea and a Pleistocene stage, that includes glaciation cycles and the creation of the present Volga River. During the first stage, the Tethys Sea had evolved into the Sarmatian Lake, that was created from the modern Black Sea and south Caspian, when the collision of the Arabian peninsula with Western Asia pushed up the Kopet Dag and Caucasus Mountains, setting definitive south and west boundaries to the Caspian basin. This orogeneic movement was continuous throughout the years, while Caspian was regularly disconnecting from the Black Sea. In the late Pontian, a mountain arch rose across the south basin and divided it
Caspian tern Caspian tern The Caspian tern ("Hydroprogne caspia") is a species of tern, with a subcosmopolitan but scattered distribution. Despite its extensive range, it is monotypic of its genus, and has no accepted subspecies. The genus name is from Ancient Greek "hudros", "water", and Latin "progne", "swallow". The specific "caspia" is from Latin and, like the English name, refers to the Caspian Sea. It is the world's largest tern with a length of , a wingspan of and a weight of . Adult birds have black legs, and a long thick red-orange bill with a small black tip. They have a