The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya.
Dolomite is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite.
The Gauja River (Koiva jõgi, Livländische Aa) is a river in Vidzeme, Latvia.
The Gauja National Park (Gaujas nacionālais parks) in Vidzeme is the largest national park in Latvia, with an area of 917.45 km² running from north-east of Sigulda to south-west of Cēsis along the valley of the Gauja River, from which the park takes its name.
Latvia (or; Latvija), officially the Republic of Latvia (Latvijas Republika), is a sovereign state in the Baltic region of Northern Europe.
The Nativity of John the Baptist (or Birth of John the Baptist, or Nativity of the Forerunner, or colloquially Johnmas or (in German) Johannistag) is a Christian feast day celebrating the birth of John the Baptist, a prophet who foretold the coming of the Messiah in the person of Jesus, whom he later baptised.
Vidzeme (Vidžemė, Vidūmō) is one of the historical and cultural regions of Latvia.