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 ...

There are some exceptions, such as tree trunks surrounded by lava and preserved as casts, but these are rare. Metamorphic rock is formed when existing rock is transformed under high heat and pressure, ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected]. Why don’t rocks burn? – Luke, age 4, New Market, ...