So difficult is the country through which the Cauca has cut its tortuous course that the fertile upper valley is completely isolated from the Caribbean, and has no other practicable outlet than the overland route from Cali to Buenaventura, on the Pacific. The upper sources of the Cauca flow through a highly volcanic region, and are so impregnated with sulphuric and other acids that fish cannot live in them.
Nevada extends thence south-eastward through Cali fornia to latitude 35.
The city was at one time an important commercial and mining centre, but much of its importance was lost through the transfer of trade to Cali and Pasto, through the decay of neighbouring mining industries, and through political disturbances.
A railway from Buenaventura will give Cali and the valley behind it, with which it is connected by over 200 m.