 As the Horezm Lake, which had been formed by the earlier Khvalinian period, expanded northwards it linked with the Aral along the Akcha Dar'ya Corridor which created what is called the Akcha Dar'ya Delta.The sands of the Aral Karakum are made up of a salt-marsh consisting of finely-dispersed evaporites and remnants of alkaline mineral deposits, washed into the basin from irrigated fields.The Karakum Desert is home to the Darvaza Gas Crater.