in length and have an only insignificant ice thickness. At glacial times, however, c. 20,000 years ago, the glaciers were over ten times longer. On the east side of this section of the Mendozina Andes, they flowed down to and on the west side to about above sea level. The massifs of Cerro Aconcagua (), Cerro Tupungato () and Nevado Juncal () are tens of kilometres away from each other and were connected by a joint ice stream network. The Andes' dendritic glacier arms, i.e. components of valley glaciers, were up to long, over thick and overspanned a vertical distance of . The climatic glacier snowline (ELA) was lowered from to at glacial times. Flora The Andean region cuts across several natural and floristic regions, due to its extension, from Caribbean Venezuela to cold, windy and wet Cape Horn passing through the hyperarid Atacama Desert. Rainforests and tropical dry forests used to encircle much of the northern Andes but are now greatly diminished, especially in the Chocó and inter-Andean valleys of Colombia. Opposite of the humid Andean slopes are the relatively dry Andean slopes in most of western Peru, Chile and Argentina. Along with several Interandean Valles, they are typically dominated by deciduous woodland, shrub and xeric vegetation, reaching the extreme in the slopes near the virtually lifeless Atacama Desert. About 30,000 species of vascular plants live in the Andes, with roughly half being endemic to the region, surpassing the diversity of any other hotspot. The small tree Cinchona pubescens, a source of quinine which is used to treat malaria, is found widely in the Andes as far south as Bolivia. Other important crops that originated from the Andes are tobacco and potatoes. The high-altitude Polylepis forests and woodlands are found in the Andean areas of Colombia, Ecuador, Peru, Bolivia and Chile. These trees, by locals referred to as Queñua, Yagual and other names, can be found at altitudes of above sea level. It remains unclear if the patchy distribution of these forests and woodlands is natural, or the result of clearing which began during the Incan period. Regardless, in modern times the clearance has accelerated, and the trees are now considered to be highly endangered, with some believing that as little as 10% of the original woodland remains. Fauna The Andes are rich in fauna: With almost 1,000 species, of which roughly 2/3 are endemic to the region, the