Rock Types and Formation
Rocks tell amazing stories about Earth's history, and there are three main types you need to know. Igneous rocks form from cooled magma and always contain crystals - tiny crystals mean the rock cooled quickly, whilst large crystals show it cooled slowly underground.
Sedimentary rocks have a grainy, layered appearance because they're made from compressed sand, mud, and other materials over millions of years. These rocks are like history books - the oldest layers are always at the bottom, with newer layers stacked on top.
Metamorphic rocks form when existing rocks get heated and squashed deep underground. Here's something fascinating: igneous rocks never contain fossils because the intense heat from volcanoes would destroy any living remains.
Memory Trick: Think "IGNeous = IGNited by fire" for volcanic rocks, and remember that anything living would be destroyed by that heat!