The following are volcanic mountains except

Monadnock of the USA is not a volcanic mountain. Volcanic mountains are formed when molten rock (magma) rises to the surface and erupts, building up layer upon layer of solidified rock and ash. Some examples of well-known volcanic mountains include Cotopaxi in Ecuador, Mount Fuji in Japan, and Mount Merapi in Sumatra. Monadnock, on the other hand, is a type of mountain called a monadnock or inselberg, which means "island mountain." These are isolated hills or mountains that rise abruptly from surrounding flat or gently sloping terrain and are often made of hard, resistant rock that has not been worn away by erosion. Monadnock is a monadnock and was formed through the uplift of a large mass of rock and the subsequent erosion of the surrounding land.