Lava solidifies as it cools and ultimately turns into solid rock. The rock formed by cooling lava varies in composition.Some rocks are dense and heavy, while others have porous compositions and are lighter in color and weight.
Lava flows out of a volcano at various speeds, and it may travel long distances before hardening or begin to turn crusty as soon as it is exposed to surrounding cooler air. The lava may collect in vast fields, which is what often happens with lava that has a watery base. According to JRank, the cooled lava from Hawaiian volcanoes may flow great distances upon release, and then it ultimately forms volcanic cones.