3. Which type of rock was precipitated from seawater as the Mediterranean Sea evaporated between 8 million years ago and 5.5 million years ago?

A) Sandstone

B) Rock salt

C) Basalt

D) Metaconglomerate

Correct Answer: Option B – Rock Salt

Rock Salt is the common name for the mineral "halite". Its chemical formula is NaCl. You might know this substance as table salt. and... Actually, rock salt is not K2SO4; it is NaCl. It can have impurities of gypsum (CaSO4) and sylvite (KCl) but it is very rare to find potassium sulfate as a mineral, although occasionally polyhalite (K₂Ca₂Mg(SO₄)₄.2H₂O ) is found associated with rock salt deposits. It is typically formed by the evaporation of salty water (such as sea water) which contains dissolved Na+ and Cl- ions. One finds rock salt deposits ringing dry lake beds, inland marginal seas, and enclosed bays and estuaries in arid regions of the world. At various times in the geologic past, very large bodies of water (such as the Mediterranean Sea and an old ocean that sat where the Atlantic Ocean sits now) also evaporated and made enormous deposits of rock salt. These deposits were later burried by marine sediments, but since halite is less dense than the materials that make up the overlying sediments, the salt beds often "punched up" through the sediments to create dome-like structures. These are now mostly burried by additional sediments.

Hence, when the sea water from the Mediterranean Sea precipitated between 8 million years ago and 5.5 million years ago, rock salt was formed.

Hence, options A, C and D are incorrect.