Igneous rocks form by the solidification of molten magma. It refers to one of the three major rocks. It can form either above or under the ground. It is always created when molten material from the inner layers of the Earth’s cool and hardens. These are some you tube links for how igneous rocks form- https://www.youtube.com/watch?v=FnoHDRPJjkw
Extra: https://www.youtube.com/watch?v=Ca1tTwun96k
Extra: https://www.youtube.com/watch?v=Ca1tTwun96k
The four types of igneous rock is Granite, Tuff, Basalt and Andesite.
http://geology.com/rocks/igneous-rocks.shtml
http://geology.com/rocks/
http://geology.com/rocks/igneous-rocks.shtml
http://geology.com/rocks/