Dead Sea hypothesis is that the Dead Sea lies in a true rift zone, an extension of the Red Sea Rift, or even of the Great Rift Valley of eastern Africa. A more recent hypothesis is that the Dead Sea basin is a consequence of a "step-over" discontinuity along the Dead Sea Transform, creating an extension of the crust with consequent subsidence. Around 3.7 million years ago, what is now the valley of the Jordan River, Dead Sea, and the northern Wadi Arabah was repeatedly inundated by waters from the Mediterranean Sea. The waters formed in a narrow, crooked bay that is
Dead Sea balsam tree, which could be made into perfume. By the 19th century, Jericho's fertility had disappeared. There are several small communities near the Dead Sea. These include Ein Gedi, Neve Zohar and the Israeli settlements in the Megilot Regional Council: Kalya, Mitzpe Shalem and Avnat. There is a nature preserve at Ein Gedi, and several Dead Sea hotels are located on the southwest end at Ein Bokek near Neve Zohar. Highway 90 runs north-south on the Israeli side for a total distance of from Metula on the Lebanese border in the north to its southern terminus at the Egyptian border