Located in the southwestern corner of Egypt known as the Uwaynat Desert (or Uweinat Desert), this huge plateau known as the Great Barrier towers over 300m above the surrounding desert. Made of sandstone and limestone it covers an area roughly the size of Switzerland. It is a remote area of rugged beauty, with dramatic cave paintings and rock carvings showing the time of human habitation in the once lush Sahara. Photos of the Gilf taken from space have been studied by NASA and it is thought to be the closest environment on Earth to the surface of Mars. The top is gravelly and featureless and it is only by looking down into the valleys caused by past water erosion that the true grandeur is revealed. It is divided into two areas- the southeastern part has well-defined, sheer cliffs and deep wadis (dried up river beds) while the northern part is fractured because it is buffeted by the sands of the Great Sand Sea and contains wider wadis. The sand blown over from the Great Sand Sea is whiter than the sand found in the Gilf Kebir itself which is red. You may also see the name spelled as Gilf al-Kebir or Jilf al-Kabir