Looking at a map of Earth, one sees a complex of mountain ranges from Southeast Asia to Spain. Almost all of these ranges are relatively young, having crumpled skyward throughout the Tertiary Period; in fact, all are still rising today, a fact made evident by frequent earthquakes across this swath of landscape.
About 55 million years ago (MYA), soon after the Rocky Mountains formed in North America, the Indian Subcontinent began to collide with southern Asia, forcing up the Himalayas and its associated ranges, from southern China to Afghanistan. By 40 MYA, the Red Sea and Gulf of Aden began to open, splitting the Arabian Plate from Africa and pushing it northward into southwestern Asia; this compressed the crust of that region, lifting the ranges of Iran, eastern Turkey and the Middle East. About the same time, as the Tethys Sea was closing, Africa drifted northward to collide with southern Europe; this has crumpled up the Alps and its associated ranges, from western Turkey and Greece to the Pyrenees of Spain. In concert, regional subduction of the African Plate beneath the Eurasian Plate has produced a chain of volcanos along the western edge of Italy.
In some areas, such as the Pyrenees, older mountain ranges, having eroded to low hills, were renewed by these Tertiary orogenies. Today, as these tectonic forces persist and the "new" mountains continue to rise, the agents of erosion combat their uplift; molded by glaciers and incised by streams, their rock dust is carried off to the sea where, millions of years in the future, it may resurface as the core of another mountain range.
