Appenzell is an alpine region, particularly in the south, where the Alpstein limestone range (culminating in the Säntis, with an elevation of ) is found, though towards the north the surface is composed rather of green hills, separating green hollows in which nestle neat villages and small towns. It is mainly watered by two streams that descend from the Säntis, the Urnasch joining the Sitter (on which is the capital, Appenzell), which later flows into the Thur. There are trams from Appenzell to St Gallen either through Gais or through Herisau, as well as lines from St Gallen to Trogen and from Rorschach to Heiden.