batholith is a smooth glassy rock that forms when lava cools.
batholith is a smooth glassy rock that forms when lava cools.
smooth glassy rock that forms when lava cools?
batholith
section::::composition of volcanic rocks.









































the sub-family of rocks that form from volcanic lava are called igneous volcanic rocks (to differentiate them from igneous rocks that form from magma below the surface, called igneous plutonic rocks).









































the lavas of different volcanoes, when cooled and hardened, differ much in their appearance and composition. if a rhyolite lava-stream cools quickly, it can quickly freeze into a black glassy substance called obsidian. when filled with bubbles of gas, the same lava may form the spongy appearing pumice. allowed to cool slowly, it forms a light-colored, uniformly solid rock called rhyolite.
volcanic rock
obsidian is the rock formed as a result of quickly cooled lava, which is the parent material. extrusive formation of obsidian may occur when felsic lava cools rapidly at the edges of a felsic lava flow or volcanic dome or when lava cools during sudden contact with water or air. intrusive formation of obsidian may occur when felsic lava cools along the edges of a dike.









































tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis.
obsidian