The Holocene extinction, sometimes called the Sixth Extinction, is a name proposed to describe the currently ongoing extinction event of species during the present Holocene epoch (since around 10,000 BCE) mainly due to human activity.
Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock (called country rock); the magma cools slowly and, as a result, these rocks are coarse grained. The mineral grains in such rocks can generally be identified with the naked eye.
Intrusive/Plutonic - Igneous rock formed when  magma solidifies deep underground (includes granites, the main rock  of the continents).     Extrusive/Volcanic - Ignâ¦eous rock formed when  magma solidifies at the Earth's surface as lava (includes basalts,  the main rock of ocean floors).