- Volcanoes can erupt under the sea, and the cooled lava can sometimes create entire islands.
- Mountains are formed when the huge slabs of rock that make up the Earth collide and are pushed up towards the sky.
- Glaciers and rivers can both cause erosion of the landscape.
5 things you didn't know
1. Volcanoes erupt below the sea too! Lava flows up towards the surface and cools, which can create islands big enough for humans are able to inhabit – like O’ahu, in Hawaii.
Stalagmites and stalactites
2. In some caves, water filled with tiny particles of rock drips from the ceiling onto the floor. Over time, these rock particles build up, creating spikes: stalagmites grow up from the floor, and stalactites grow down from the ceiling.
3. The Earth’s surface is made of huge, slow-moving sheets of rock. Sometimes, these collide and push bits of land up towards the sky, creating mountains. The tallest is Mount Everest, at 8,848 metres.
4. Glaciers are massive slabs of ice that form on top of mountains. When they become too heavy, they slide down, carving and scraping away the land below to create deep valleys. The removal of land is called erosion.
5. Rivers can also cause erosion. Scientists think the Grand Canyon was formed because the Colorado River cut its way through layers of rock, but they just can’t work out how old it is! Their estimates vary from 5 million to an astounding 70 million years.
Spark a discussion
- How are stalagmites and stalactites created?
- What causes mountains to form?
- How can glaciers and rivers affect the landscape?