What is clay?

I recently saw an advert which claimed, “wet soil makes clay”. This statement is completely wrong, but it got me thinking about how we trust the things we see in the media and how we, as part of a global company, have a responsibility to make sure everything we publish is factually correct.

So, what is clay, if not “wet soil”?

Clay is the name given to sediment that is under two micrometres in diameter. Soil is typically defined as the top layer of the Earth’s surface which provides the medium for plant growth. Soil very often contains clay, but it also contains larger sediments such as sand and gravel, dead plants and animals, and air and water. This combination of components varies wherever you are and is even different from one side of a field to another. Different soils have different properties: for instance, one might be more nutrient rich, while another may have a higher clay content. This variation is a result of the natural processes of bedrock weathering and organic material decomposition that, together, produce what we recognise as soil.

The distinction between soil and clay might not be of critical importance to you unless you’re an avid gardener who knows the importance of drainage or a geotechnical engineer working with site excavations.

Within RSK, we have a range of soil experts. Some specialise in agricultural soils and understand soil as a resource. Some are engineers and work with the geophysical properties of soil to ensure developments are safe and stable, in the short and long term. Did you know we have earth scientists in the Communications team, too? When a client asks us to write about anything to do with earth science – especially soil – they can be confident that we know what we’re talking about.

Maybe the publishers of that advert should have asked us to write their script!