Abstract: An apparatus and method are provided for treating base materials, such as ore of a leach pad in a precious metal mining operation. A tilling head of the apparatus includes a cutter having a cutting face for engaging and loosening compacted base materials. The tilling head is extended into the base material down to a tilling depth so that the cutter moves loosened base material up and over the top of the tiller apparatus before depositing it in a pile opposite the cutting face. The loosened base material is deposited a distance from the tilling head that is sufficient to create a void between the tilling head and the pile that extends down to the tilling depth to prevent the loosened base material from being disturbed by the tilling head. The tilling head can be positioned so that the cutting face undercuts the base material to thereby assist the cutter in moving the loosened base material and increase the distance between the tilling head and the pile.