views updated

Jökulsá (yö´külsou), name of several Icelandic rivers formed by glaciers. The best known is the Jökulsá á Fjöllum, which rises on the north slope of the Vatnajökull in SE Iceland and flows c.130 mi (210 km) N into the Öxarfjörður bay, forming the Dettifoss, one of four waterfalls on the river and one of Europe's most powerful waterfalls, c.30 mi (50 km) from its mouth; below the falls, the falls the river flows through the Jökulsárgljúfur, a canyon that is 390 ft (120 m) deep in places.