1. The Beginning: Molten Rock
* Lava starts as molten rock, incredibly hot and fluid, erupted from a volcano.
* This molten rock is called magma when it's underground and lava when it flows on the surface.
2. Cooling Down
* As lava flows, it begins to cool and lose heat.
* The rate of cooling can be influenced by factors like:
* The environment: Air-cooled lava cools faster than underwater lava.
* The volume of the lava flow: A thin lava flow cools faster than a thick one.
3. Crystallization
* As the lava cools, its minerals start to crystallize.
* These crystals grow in size and shape as the lava continues to cool.
* Different minerals crystallize at different temperatures, so the cooling process can be seen in the composition and texture of the resulting rock.
4. Formation of Igneous Rocks
* When the lava cools completely, it solidifies into igneous rocks.
* The type of igneous rock formed depends on:
* The composition of the original lava: For example, lava rich in silica forms rocks like granite or rhyolite, while lava with less silica forms rocks like basalt or gabbro.
* The rate of cooling: Slow cooling allows for large crystals to form, while fast cooling creates smaller crystals or even glassy textures.
5. Examples of Igneous Rocks
* Basalt: A dark, fine-grained rock formed from rapidly cooled lava.
* Granite: A light-colored, coarse-grained rock formed from slowly cooled magma.
* Obsidian: A black, glassy rock formed from lava that cooled very quickly.
* Pumice: A light-colored, porous rock formed from frothy lava.
In short, lava turns into rock through the process of cooling and crystallization, resulting in a diverse array of igneous rocks with unique characteristics.
