An introduction to geology
An introduction to geology

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

An introduction to geology

4.2 Geological (extraction) in your pocket

You looked at how we extract rocks and minerals in Week 2. In the first part of this week, you are going to look at something slightly different – the aggregate industry. This is sand, gravel and crushed stone, and it’s quite understandable if this is something you’ve not thought about too much before. All the concrete in the world has to have gravel and sand within it, and it has to come from somewhere. Globally, twice as much concrete is produced as plastic, steel, aluminium and wood combined, and over 70% of the world’s population lives in concrete buildings.

Described image
Figure 4.1 Sand, gravel and stone

Now, you may be wondering what the difference between gravel and crushed stone is. Well, gravel is naturally occurring small stones, whereas crushed stone has been created by breaking up larger pieces of rock. Generally, gravel clasts will be slightly more rounded than crushed stone, and will also often contain many different types of rock, while crushed stone is normally one type of rock that has been broken up.

Activity 4.1 Gravel and sand

Timing: Allow about 5 minutes

Think about where gravel and sand could come from. Make some quick notes below if anything comes to mind. In the next section, you will look at this further.

To use this interactive functionality a free OU account is required. Sign in or register.
Interactive feature not available in single page view (see it in standard view).

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371