At http://phys.org/print290325427.html … there is a lovely image of the Sinai peninsular overlain with the drainage network of Wadi el-Arish. According to a new study the traces of an ancient watershed in the Sinai Desert, from ten to five thousand years ago, is discernible. The Wadi el-Arish was once a major river with tributaries in the early half of the Holocene.
At http://phys.org/print290340897.html … we learn that feldspar dust plays an important role in the creation of ice in clouds. A paper in Nature reveals that feldspar plays an important role in many things – besides making interesting crystals. It makes up 60 per cent of the Earth's crust and occurs as dust in clouds – presumably getting there from dry regions such as the Sahara Desert.
Feldspars are a family of silicate minerals which occur in igneous rocks. Calcium, sodium and potassium are also present and one of these elements is usually dominant – but most feldspars contain all three (see http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry34.html