Sedimentary rocks are formed by small rock pieces which are transported by rivers and laid down in layers. Chalk is a sedimentary rock. Metamorphic rocks are formed when another rock is under heat ...

For example, small pebbles of rock are rolled along a river-bed. 2 Deposition In deposition, sediment which was carried in transport is laid down. 3 Sedimentation Layers of sediment form on top of ...

If you buy through a BGR link, we may earn an affiliate commission, helping support our expert product labs. A group of scientists has discovered a hidden layer of molten rock under the Earth’s ...

Led by Curtin University geologists Chris Kirkland and Tim Johnson, a research team unearthed this primeval crater beneath ...

The next layer is the mantle. Many people think of this as lava, but it's actually rock. The rock is so hot, however, that it flows under pressure, like road tar. This creates very slow-moving ...

"Shorelines are great locations to look for evidence of past life." Today, Mars is a chilly desert of rock and dust — but 4 billion years ago, the planet had rivers, lakes and even oceans with sandy ...