<P> Extrusive igneous rocks , also known as volcanic rocks , are formed at the crust 's surface as a result of the partial melting of rocks within the mantle and crust . Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks . They are formed by the cooling of molten magma on the earth 's surface . The magma , which is brought to the surface through fissures or volcanic eruptions , solidifies at a faster rate . Hence such rocks are smooth , crystalline and fine - grained . Basalt is a common extrusive igneous rock and forms lava flows , lava sheets and lava plateaus . Some kinds of basalt solidify to form long polygonal columns . The Giant 's Causeway in Antrim , Northern Ireland is an example . </P>
<P> Extrusive igneous rocks , also known as volcanic rocks , are formed at the crust 's surface as a result of the partial melting of rocks within the mantle and crust . Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks . They are formed by the cooling of molten magma on the earth 's surface . The magma , which is brought to the surface through fissures or volcanic eruptions , solidifies at a faster rate . Hence such rocks are smooth , crystalline and fine - grained . Basalt is a common extrusive igneous rock and forms lava flows , lava sheets and lava plateaus . Some kinds of basalt solidify to form long polygonal columns . The Giant 's Causeway in Antrim , Northern Ireland is an example . </P>
what is an example of an intrusive igneous rock
what is an example of an intrusive igneous rock
Basalt
Basalt