There are many kinds of rock, but we usually divide them into three groups: (a) those laid down under the sea, in a river or in a desert, (b) those that come from volcanoes, and (c) those that were formed deep under mountains.
Here are examples of all three types and how to recognise them...
Playing time: 8 minutes. This is a long movie with much detail and is best shown more than once. (For hints on using videos click here.)
