Brno Centre Geotrail – Rocky outcrop under Petrov

A long time ago (probably 750 million years ago), Brno lay at the bottom of an ocean, or, more exactly, on a mid-ocean ridge (like the one in the middle of the Atlantic) from which lava spewed. Later, under great pressure and heat, it underwent metamorphic processes so that rocks we call metabasalt appeared and their outcrops can be seen under Petrov. During turbulent times, the large rock masses broke and formed orogens, with some of the rocks being raised, thus creating horsts. Today, these are the most dominant features of the city centre: Petrov and Špilberk. Other distinctive elevated places (Kraví hora, Palackého vrch) have similar morphology. Špilberk and Petrov aren’t volcanoes, as people sometimes mistakenly say, but “just” broken and raised pieces of hardy volcanic rocks.