Irrigation Works
It was in works of irrigation, however, that the race exhibited its greatest engineering genius. In the valley of Nasca the Incas cut deep trenches to reinforce the irrigating power of a small river, and carried the system high up into the mountains, in order that the rainfall coming therefrom might be conducted into the needful channel. Lower down the valley the main watercourse is deflected into many branches, which irrigate each estate by feeding the small surface streams. This system adequately serves the fifteen estates of Nasca to-day! Another high-level canal for the irrigation of pasture-lands was led for more than a hundred and fifty miles along the eastern slope of the central cordillera.