FORMATION OF IGNEOUS ROCKS
Igneous rocks form
from molten rocks, which are thick, fluid masses of very hot
elements and compounds. There are many different types of igneous rocks.
However, they were once melted and have since cooled down. The two major
factors that influence the creation of igneous rocks are the original
rock that was melted and the cooling history of the molten rocks.
The original rock could be any initial rock.
Plate tectonic mechanisms move rocks throughout the crust, so even
sedimentary and metamorphic rocks can become melted again in a
subduction zone. The different types of rocks melt into different
chemical magmas, which then is dependant on how it cools.
Molten rock with different cooling histories and
different chemical composition will form different igneous rocks. If magma
cooled inside the crust of the Earth, the rocks will have larger minerals and
referred to as plutonic or intrusive rocks. Molten rock
that flows out onto the surface is called lava. These rocks are
called volcanic or extrusive rocks.
Granite boulder reveals where these rocks