The most popular alcoholic drink in Switzerland is wine. Switzerland is notable for the variety of grapes grown because of the large variations in terroirs, with their <answer>specific mixes of soil, air, altitude and light</answer>. Swiss wine is produced mainly in Valais, Vaud (Lavaux), Geneva and Ticino, with a small majority of white wines. Vineyards have been cultivated in Switzerland since the Roman era, even though certain traces can be found of a more ancient origin. The most widespread varieties are the Chasselas (called Fendant in Valais) and Pinot noir. The Merlot is the main variety produced in Ticino.
What 4 terrain variations are credited for Switzerland's notable variety of grapes grown?
specific mixes of soil, air, altitude and light