Eli5: what exactly is clay? How is it different from regular dirt or loam?

Question

Eli5: what exactly is clay? How is it different from regular dirt or loam?

In: 16

Answer 1

As a young man I worked as a soils mechanic for a construction company.
Clay is flat particles smaller than 200 parts per inch. Silt is round particles, smaller than 200 parts per inch.
Dirt is what gets swept up when you clean the floor. Soil is all of the stuff that you see when you dig into the ground.
Clay is sticky because when they get wet, the flat particles stick to one another. Round particles do not stick together.