Deep fjords indent the coasts of Iceland, particularly in the north and west. The island itself is a geologically young basalt plateau, averaging 2,000 ft (610 m) in height (Öraefajökull, c.6,950 ft/2,120 m high, is the highest point) and culminating in vast icefields, of which the Vatnajökull, in the southeast, is the largest. There are about 200 volcanoes, many of them still active; the highest is Mt. Hekla (c.4,900 ft/1,490 m). Hot springs abound and are used for inexpensive heating; the great Geysir is particularly famous. The watershed of Iceland runs roughly east-west; the chief river, the Jökulsá, flows N into the Axarfjörður (there are several other rivers of the same name). 2 The climate is relatively mild and humid (especially in the west and south), owing to the proximity of the North Atlantic Drift; however, N and E Iceland have a polar, tundralike climate. Grasses predominate; timber is virtually absent, and much of the land is barren. Only about one fourth of the island is habitable, and practically all the larger inhabited places are located on the coast; they are Reykjavík, Akureyrí, Hafnarfjörður, Siglufjörður, Akranes, and Isafjörður. 3 The Lutheran Church is the established church and more than 95% of the people are members of it, but there is complete religious freedom. The official language is Icelandic (Old Norse). Virtually all Icelanders are literate; they read more books per capita than any other people in the world. There is a university (est. 1911) at Reykjavík.