FTA: > The key requirement is a deep hole in the ground; it could be a disused mineshaft brought back into use, or it could be a purpose drilled or sunk shaft.

FTA: > The key requirement is a deep hole in the ground; it could be a disused mineshaft brought back into use, or it could be a purpose drilled or sunk shaft. So, apparently, "sinking" a shaft involves making a hole using some technique other than drilling. What technique is that? Dictionaries are no help. Wikipedia[1] says: > Shafts may be sunk by conventional drill and blast or mechanised means. "Mechanized means" is pretty vague. Can anyone clarify? [1] https://en.wikipedia.org/wiki/Shaft_mining https://en.wikipedia.org/wiki/Shaft_mining