Windstreak
Videos
A windstreak is a planetary surface feature of aeolian origin characterized by an albedo that contrasts with surrounding surface in an elongated pattern. Windstreaks are associated with topographical
An example of a windstreak, at a volcano on Mars
Clay
Videos
Clay is a type of fine-grained natural soil material containing clay minerals. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as
Boulder clay cliff south of Withernsea, England
A 23,500 times magnified electron micrograph of smectite clay
Italian and African-American clay miners in mine shaft, 1910
Clay layers in a construction site in Auckland, New Zealand. Dry clay is normally much more stable than sand in excavations.