* Intrusive means that the magma (molten rock) cooled and solidified *inside* the Earth's crust.
* Extrusive igneous rocks, on the other hand, form when lava (magma that has erupted onto the surface) cools and solidifies.
Characteristics of Intrusive Igneous Rocks:
* Slow Cooling: Since they cool slowly underground, intrusive rocks have larger crystals (visible to the naked eye). This is because the minerals have more time to grow and arrange themselves.
* Coarse-Grained Texture: The large crystals create a coarse-grained texture.
* Examples: Granite, Gabbro, Diorite, Peridotite
Examples of Intrusive Igneous Rock Bodies:
* Batholiths: The largest intrusive bodies, covering hundreds of square kilometers.
* Stocks: Smaller versions of batholiths.
* Dikes: Sheet-like intrusions that cut across existing rock layers.
* Sills: Sheet-like intrusions that are parallel to existing rock layers.
Let me know if you'd like to learn more about specific intrusive rocks or their formation!
