40d:Volcano

Volcanoes are named mountains that additionally provide a source of magma.

Volcanoes seem to be placed randomly in the world, and they are not always associated with mountains or other rocky terrain. They can even appear in the middle of oceans, as volcanic islands.

In the fortress mode location chooser, volcanoes are only visible on the "region" and not the "world" map. Scroll around the world looking for a red ^ in the regional map - or, alternately, look at an exported map of your entire world, which does include details such as volcanoes. After selecting the space that indicates a volcano, move the starting area shown on the "local" map to include the square with a dark red ≈, which is an actual magma vent. There may also be additional local magma vents in nearby tiles around the volcano.

Magma vents can very occasionally appear in locations distant from volcanoes. However, genuine volcanoes sometimes have other interesting features, similar to named mountains: they are frequently sites for caves, often have a wider than usual variety of stone and ore, and may include unusual features such as cave rivers, chasms or pits.