The scarcity of water along southern coast of Peru has conditioned all aspects of life, since the first settlers moved into region. The Nazca River basin often remains bone dry until December, when the snow-capped summits of the nearby Andean mountains begin to melt from the rising summer temperatures [Endnote 1]. For the next few months, cool water cascades down the canyons of the upper elevations, refilling many of the coastal rivers, streams and washes, and replenishing the underground aquifers. Only through extensive irrigation are the dry riverbeds transformed into verdant oases, some of which can stretch from the seashore to the mountains, like dark green ribbons laid across the pale desert sands.