Darwin's worm-stone at Leith Hill

A wooden trail waymaker with an orange cap sits next to a large stone nestled in the grass in the field below Leith Hill Place.

Charles Darwin’s worm-stone still sits within the grounds of Leith Hill Place today. Previously left on the foundations of a kiln within the estate, these stones were made of quartzose sandstone.

A sinking stone

Darwin noted that earth had started to bank-up the sides of the stone and that the stone itself had sunk into the ground.
 

Earthworms

 
He concluded that parts of the stone became buried by the action of earthworms excavating soil from beneath and depositing it above the surface. He also believed that this was the same way that ancient ruins eventually became buried in the ground.
 

A lengthy deposit

 
From measurements taken, it has been estimated that a 25cm thick stone might take approximately 250 years to fall to the level of the ground.
 
It was estimated that as much as 16 tons of material can be deposited on an acre of field in one year. This material can reach a thickness of 5cm in ten years and is made possible by the action of approximately 25,000 worms.