A man digging a pit found that he could dig with ease initially but digging became difficult as he went deeper. He could not dig beyond a depth of 5 feet. Provide a suitable scientific explanation.

It is easier to dig soil initially because the upper layer of the soil consists of topsoil and subsoil. These two horizons are composed of loose soil particles and easy to dig. At the deeper layers, partially weathered rocks or bedrocks are present. It is very difficult to dig through partially weathered rocks or bedrocks.