natural or man made?

I was recently travelling in Nigeria.

On JOS Plateau in Central Nigeria, one finds intriguing rocks formations. When asked the origins of such perfectly balanced configurations, local people answer it is natural.

Unless these rocks used to be covered of a thick layer of earth that has been washed out by a diluvial rain, it is difficult to figure out a natural phenomena that would have delicately set the upper bigger rocks onto the smaller ones. They cannot have fallen down onto them, because the speed of the falling object would have caused the rock to blast at the location of the impact.

Plus, the same type of improbable configuration is visible in several different sites across the Plateau, which makes the “natural hypothesis” even less likely. Diluvial rain or mysterious architects?