Valais is Switzerland’s largest wine-growing canton and one of its southernmost wine regions. Its vineyards running along the upper Rhône valley between the Pennine and Bernese Alps. It is Switzerland's driest and sunniest wine region, a semi-continental climate long tamed by the bisses, glacier-fed irrigation channels that have watered these slopes since at least the thirteenth century. The valley's geology shifts from gneiss and schist on the steep valley walls to glacial moraine and calcareous soils lower down, giving Valais a stylistic range unmatched by any Swiss region of comparable size. Around a third of plantings are indigenous, among them Petite Arvine and Amigne for the whites, Cornalin and Humagne Rouge for the reds. At Visperterminen, vines reach 1,100 metres, among the highest permanent vineyards in Europe.