Iceland is a big piece of land that stands on top of some very special rocks. These rocks are called tectonic plates. Imagine if you had a few big puzzle pieces that fit together and moved around. That's what the tectonic plates are like.
One of these plates is moving underneath another plate, and it's pushing up the land of Iceland like it's on a big conveyor belt. When this happens, it causes lots of earthquakes and volcanic eruptions. These eruptions happen because the volcanic rock deep below the ground can’t handle the pressure and explodes.
The volcanic eruptions also create brand new pieces of land and make Iceland even bigger! Some parts of Iceland are covered in dark lava rock, which is created when the lava cools down and hardens. Other parts of Iceland have layers of ash, which is what’s left over after a volcanic eruption.
There's also lots of ice in Iceland, and that ice formed a long time ago when snow began to pile up on the top of the mountains. It was so heavy that it started to flow down the mountains, creating glaciers. These glaciers carved out big valleys and left behind all kinds of rocks and stones.
So basically, Iceland is a really cool place with lots of different types of rocks, all because of the tectonic plates moving around and the volcanic eruptions and glaciers.