What is a dense mix of dry hot rock fragments and hot gas erupting from volcanic vent at high speed is

Magma is called for the dense mix of dry hot rock fragments and hot gas erupting from volcanic vent at high speed. Gas bubble, making up the lave are energetic in nature, because they keep on expanding in all directions, they will go all out to the only open are of a volcano, the vent, in an upward direction. 

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.