Metamorphic rocks are the third main classification. These started out as other types of rock but were changed by high heat and pressure. In this article, we'll list 30 types of rock with pictures ...

A compound is a substance that contains two ... rock. Sedimentary rocks are formed by small rock pieces which are transported by rivers and laid down in layers. Chalk is a sedimentary rock ...

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 curiouskidsus@theconversation.com. Why don’t rocks burn? – Luke, age 4, New Market, ...