Question

Passage

For decades, geologists puzzled over thick layers of salt buried deep beneath the floor of the Mediterranean Sea. In the 1970s, deep-sea drilling vessel *Glomar Challenger* recovered sediment cores containing gypsum and rock salt, minerals that only form when saltwater evaporates in shallow basins or salt flats. This discovery challenged the long-held assumption that the Mediterranean had always been a deep, water-filled basin.

To explain this salt, scientists proposed the Messinian Salinity Crisis hypothesis. The argument begins with tectonic uplift: the shifting of the African and Eurasian plates pinched closed the Strait of Gibraltar, the Mediterranean’s sole connection to the Atlantic Ocean. Cut off from its water source, the Mediterranean began to dry out rapidly under the hot Mediterranean sun, as evaporation vastly exceeded the inflow from rivers.

As the sea level plummeted, the basin was transformed into a deep, desert-like sinkhole thousands of feet below sea level, covered in vast salt flats. This extreme dryness persisted for hundreds of thousands of years, creating the massive salt deposits observed today. Finally, the barrier at Gibraltar breached, resulting in the Zanclean flood—a catastrophic deluge where Atlantic water re-entered the basin, refilling the Mediterranean in a matter of months or years.

Question

The passage presents the scientific explanation of the Messinian Salinity Crisis. Based on the passage, arrange the following steps in the order that the author introduces and develops the central argument, starting with the initial presentation of the geological mystery.