lesson
Updated 6 days ago
Pick up any pebble from the ground. That tiny rock might have blasted out of a fiery volcano, settled at the bottom of an ancient ocean, or been squashed deep inside a mountain!
Geologists group every rock on Earth into just three main rock types based entirely on the recipe nature used to make them.
What happens when melted liquid rock cools down and turns solid?
1. Igneous Rocks: Born from Fire
Igneous rocks form when super-hot melted rock cools down and hardens into solid stone.
If the melted rock is trapped underground, it is called magma, but once it erupts onto Earth's surface, it is called lava.
๐Create an interactive visual diagram of igneous rock formation. Show a cutaway volcano. Underground, show an orange-red magma chamber with a callout pointing to 'Granite' (slow cooling creates visible crystal specks). On the surface, show glowing lava pouring out with two callouts: 'Basalt' (fast cooling makes dark rock) and 'Obsidian' (super-fast cooling makes shiny volcanic glass). Include toggle buttons for 'Underground (Magma)' and 'Surface (Lava)' that highlight the respective rock examples and their cooling speeds. Use cheerful colors: warm volcano hues (#f97316, #ef4444), dark stone (#334155), clean light background (#f8fafc), responsive container max-width 480px.
When magma cools slowly underground over thousands of years, it grows large, speckled crystals like granite.
When lava shoots out into the cool air or ocean water, it chills so fast that it forms smooth, glassy rocks like obsidian or bubbly rocks like pumice.
Over millions of years, wind and rain crumble solid rocks into dust and sand โ so where does all that loose grit go?
2. Sedimentary Rocks: Built in Layers
Sedimentary rocks form when tiny pieces of sand, mud, and crushed shells โ called sediments โ pile up in thick layers and get squished together over millions of years.
Rivers carry these sediments into lakes and oceans, where heavy upper layers press down like a giant trash compactor until natural minerals glue the grains together.