One cause that appears obvious and easy of acceptance is leaching.
Water undermines by washing away the softer parts and by leaching.
This leaching process concentrates these minerals as ore that can be mined.
A good illustration of leaching is found in the manufacture of potash.
It in part prevents the leaching out of the soluble parts of the ash.
This may be residues from roasting and leaching pyrites for vitriol, etc.
There is no waste from leaching, as when the manure lies exposed to the weather.
It has two Parts: one on the acquisition of knowledge; the other on Communication or leaching.
Water may be lost from the soil by leaching through the lower soil.
The disadvantage of such soils is that they lose their fertility by leaching.