Track 50

Track 50.

1. You can use this machine to make a hole in something. For example, you use a small one to make a hole in the wall to hang a picture, or a big one to make a hole in the ground.

2. This is a hole in the ground which is dug in order to extract water, oil or gas.

3. This is a kind of rock deep in the ground that isn’t very hard and is easy to break.

4. This is a narrow space which appears inside rock when the rock breaks.

The space can fill up with water or gas.