By cooling and then hardening.
volcanoes form when there is a crack in the earth's crust and a chamber of hot rocks(magma chamber) builds up pressure and eventually lava flows out of the crack
No. Plutonic rocks are igneous rocks that hardened underground. Rocks that form on volcanoes are volcanic rocks.
Because the lava from volcanoes form igneous rocks
Igneous Rocks.
http://en.wikipedia.org/wiki/Volcano volcanoes can be composed of a variety of igneous rocks.
igneous rocks,sedimentary rocks, and metamorphic rocks.
Rocks formed in volcanoes from magma.
Igneous rock is found in volcanoes.
The plural possessive form of "volcanoes" is "volcanoes'".
tomatoes
no not all rocks are formed by volcanoes because what about sedimentary rocks which are the rocks formed over a long period of time by little pieces of sand and rock etc. by wind and water
All volcanoes produce igneous rocks.