Basalt forms when magma cools very quickly. basalt

-has small crystals
-is an intrusive igneous rock
-forms from heat and pressure
-forms from contact metamorphism

places of higher salinity. there are parts of the ocean where hardly any rain falls but warm dry winds cause lots of evaporation. this evaporation removes water – when water vapour rises into the atmosphere, it leaves the salt behind, so the salinity of the seawater increases. this causes the seawater to become denser.