A qanat is a water management system used to provide a reliable supply of water to human settlements or for irrigation in hot arid and semi-arid climates. The technology is known to have developed in ancient Persia, and then spread to other cultures, especially along the Silk Road, indeed there are still many examples of qanat systems in Spain, most likely brought to the area by the Moors during their occupation of the Iberian peninsula.
An important rock-forming silicate mineral composed of silicon-oxygen tetrahedra joined in a three-dimensional network. Quartz forms the major proportion of most sands and is widely distributed in igneous, metamorphic and sedimentary rocks.
The latest period of geologic time, covering the most- recent 2,000,000 years of the Earth's history. It is divided into two epochs: the Pleistocene (2 million years ago to approximately 10,000 years ago) and the Holocene (the period from approximately 10,000 years ago to the present). The Quaternary period is the artificial division of time separating pre-human and human periods. It contains five ice ages and four interglacial ages, and temperature indicators seem to show sharp and abrupt changes by several degrees.