Domestic cats want their fur to be full of particles of dusty earth

There is no doubt in my mind that my cat wants his coat to be full of dusty earth which is why he rolls around on dusty ground at the end of my backyard. He is lying on my bed as I type this which has exposed the copious amounts of soil in his coat as it is deposited on the white sheets. 

What I am saying looks counterintuitive because cats are fastidiously clean and committed self-groomers. But they don't see dusty earth as dirt. They must see it as a beneficial material to assist their health.

I'll have to hoover the bed again. It is happening daily in the dry weather. Actually, it is an official drought in the UK and it is driving me mad. But my cat thinks that dirt in his fur is good for him. It must be. It must help deal with skin parasites and remove them from the fur.

It seems that the parasites get caught up in the dirt and removed. Only my cat does not have any skin parasites (ectoparasites) such as fleas or ticks. But he rolls in dirt instinctively to remove ectoparasites.

My cat Gabs after he rolled around in the dirt. CLICK ON THE IMAGE TO SEE IT NICE AND BIG. YOU'LL SEE THE DIRT BETTER!

Rolling around in dirt must only be done because it is instinctively beneficial to the cat. They just don't mind it when their fur has a ton of dirt in it. He's just come onto my legs so he'll deposit more dirt over me now.