🪨 Rocks and pebbles

Rocks are made of tiny building blocks called minerals, packed and pressed together so tightly that they feel solid and hard. Different rocks have different minerals mixed inside them, which is why some rocks are grey and plain while others sparkle or show colourful speckles. The same rock can look completely different once it is cut open or polished, revealing patterns hidden inside.

A rock feels hard and heavy, and some rocks are smooth while others feel rough and bumpy.

Rocks can be grey, brown, white, or even a little sparkly, every rock has its own color.

A rock stays rough and sharp when it has just broken off from a bigger piece of rock. Water, wind, and other rocks slowly wear away those sharp edges over time, the same way sandpaper smooths down rough wood. The longer a rock rolls around in a river or gets blown by wind, the smoother and rounder it becomes.

A pebble is a very small, smooth rock, often found near a path, a beach or a river.

Pebbles start out as bigger, rougher chunks of rock that break off from cliffs or larger stones somewhere upstream or nearby. As they get pushed along by flowing water, or rolled underfoot on a path over and over, their sharp corners keep knocking into other rocks and slowly wearing away. Given enough time, all those tiny bumps and scrapes add up until the pebble ends up round and smooth in your hand.

Yes, rocks keep slowly changing, even though one rock looks the same from one day to the next. They crack, they wear down, or they get squeezed and heated deep underground. Given enough years, water and ice can even split a huge boulder clean in half by freezing inside a tiny crack and pushing it apart. Some rocks that look like piles of loose gravel today were once part of a solid mountain that slowly crumbled away.

A big rock has a lot of hard material packed tightly inside it, which makes it heavy to lift.