Andes, the coastal range and the central Valley- and a series of latitudinal ald altitudinal climatic regions. In the north, approximately to latitude 27 grades, the Andes consists of two or more almost parallel ranges. Mountain passes in this part of the Andes are few and difficult, rising above 10,000 feet. South of Santiago the Andes become gradually lower, with peaks of aproximately 12,00 feet.
Passes are much lower and easier to negotiate.
The mountains extend trough the island of Tierra del Fuego to the southern end of the continent. Near the Chilean Andes and along their western flank is one of the world's densest concentrations of volcanoes, both extinct and active. There are over 2,000, including 48 that have erupted at least once within the last 100 years. The abundance of volcanic features in Chile and its vicinity is also reflected in the frequent sismic events and conspicous evidence of recent tectonic movements. It rises abruptely from the shoreline in high cliffs that for hundred of miles form an unbroken wall, creating a coastline devoid of natural harbors and a formidable obstacle to acess inland.