Crustal weaknesses before 500 Ma influenced continental rifting, as the Arabian peninsula moved away from Africa, and the formation of the Red Sea Basin at the start of the Oligocene. By then, some of the Paleozoic and Mesozoic rocks had been eroded, if ever deposited. In fact, the 1200 km wide ANS orogenic belt, has a present-day layered crustal structure, with a uniform Moho depth of 35–45 km. Post-rift deposition of evaporites occurred until the Pliocene, when a marine environment took over.