On either side of the Nile Valley the desert plateau extends from the southern borders of Egypt to the Delta in the North. Between the Nile and the Red Sea the width of the wilderness varies from 90 to 350 miles and is known in the north as the Arabian Desert. On the west the Desert of Libya has no natural barrier for hundreds of miles; it is indeed a part of the immense Sahara Desert, to many minds, is synonymous with monotony, flatness and aridity. This is only a half-truth, for the scenery of the desert offers, to the observant eye, as much variety as a fertile landscape. In the North of Egypt the desert is certainly flat but from Cairo southwards it rises to 1000 and even 1500 feet above sea level in a series of terraces or small plateaus rising one above the other and intersected by small ravines worn by the occasional rainstorms which burst in their neighborhood. These plateaus, with occasional hills, cut up by valleys (wadis) and sometimes by deep ravines constitute the principal type of scenery of the Egyptian Deserts. In the Arabian Desert it ends on the Eastern Side in a chain of mountains running parallel to the Red Sea and the Gulf of Suez.