The mountains of the world have been pushed up from the surface of the Earth in different ways. Some mountains are volcanoes. Some are dome mountains, pushed up by rising magma that does not reach the surface. Some mountains grew when rocks were squeezed up into great folds, while others are blocks of land pushed by the movements of the Earth's plates.
The world's greatest mountain ranges were formed by sideways pressure, caused when plates pushed against each other. The rocks that make up some of the world's highest peaks were formed on the ocean floor. Over thousands of years, these rocks were squeezed up into great folds.
The world's highest peak on land is Mount Everest in the Himalayas. It is 8,850.1728 m ( 29,036 ft ) tall. The world's highest mountain, from its base on the ocean floor, is Mauna Kea, on Hawaii. It is 10,203 m high or
( 33,474 ft ) but only 4,205 m ( 13,796 ft ) is above sea level. The biggest rift valley runs through East Africa into southwest Asia and is 5,600 km ( 3,500 miles ) long.