New fold mountains are often associated with convergent boundaries. When plates collide and the crust folds upward to form mountains, the subduction of the oceanic plate underneath simultaneously creates magma. This is why many of the world’s highest peaks in the Andes or the mountains of Indonesia and Japan are actually volcanic. This geographic overlap between “folding” (crustal shortening) and “volcanism” (magmatic activity) occurs because both processes are driven by the same massive tectonic forces at the edges of moving plates.