[Image: A satellite view of “two huge sand dune seas in the Fezzan region of southwestern Libya.” These are “sprawling seas of multi-storey sand dunes known as ‘ergs’. The Erg Ubari (also called Awbari) is the reddish sand sea towards the top of the image. A dark outcrop of Nubian sandstone separates the Erg Ubari sand from the Erg Murzuq (also called Murzuk) further south.” See earlier for more satellite imagery].