"Cleanse the Earth Stone" is an objective in the main quest "Cleansing the Stones" in Elder Scrolls V: Skyrim - Dragonborn.
Head to the Earth Stone nearby to the West Raven Rock. Fast Travel there and then be ready for the next part.
Approach and cleanse the stone using the Bend Will Shout.
This time, there will be 2 Lurkers (Or 1, based on difficulty) that you will have to defeat. 1 will appear close to you by the Earth Stone.