Aerial photograph of Bozen quartz porphyry, South Tyrol, Italy. Nearly 280 million years ago, when the supercontinent Pangaea began to break up, cracks opened in the Earth?檚 crust. Around 1000 degree Celsius hot lava streams and pyroclastic flows gushed out of volcanoes. Cooled down, they became the red coloured Bozen quartz porphyry, which built up the prominent colourful walls around Bozen in South Tyrol, a part of the Italian Alps. It forms the base of the Dolomites.