the Eurasian plate. Some of the Indian plate was thrust beneath Asia and some of Asia was
thrust onto India. Rock also folded, which thickened the crust and formed the mountains.
In places, the old seafloor that was between the two slabs of continental crust have been
thrust over the Asian continent and are found high in the Himalayas (Figure7.21).
Figure 7.20: The India plate collides with the Eurasian plate to form the world’s largest
mountain range, the Himalayas. ( 23 )
Figure 7.21: The Himalayas are the world’s highest mountain range. ( 5 )Subduction of oceanic lithosphere at convergent plate boundaries also builds mountain
ranges. The Andes Mountains are a chain of continental arc volcanoes that build up as
the Nazca plate subducts beneath the South American plate (Figure7.22).
Rifting at a divergent plate boundary can also build mountain ranges. When crust is pulled
apart, it occupies more area. The crust breaks into blocks that slide up and down along the
normal faults that separate them. The result is alternating mountain ranges and valleys,
known as a basin-and-range (Figure7.23). The state of Nevada is the center of a classic
basin and range province (Figure7.24).