Changes

[[Image:Stone_hammer_well_drilling_icon.png|right]]

The previous drilling methods are not suitable for hard soil formations, so ongoing development led to the Stone-hammer. This method consists of a heavy hammer hitting directly on a hollow drill-head. Although it does not penetrate very hard stone such as basalt, it is a tougher option than the Rota-sludge method. This technology is being refined further in India and Nicaragua.