We explain what the subsoil of the Earth’s crust is and what its components are. In addition, we tell you why it is controlled by the State.

The soil and subsoil layers have different colors depending on their components.
Although it lacks organic matter, the subsoil offers minerals and water to the deepest roots.

What is the subsoil?

The underground It is the intermediate layer of the Earth’s crust that is below the superficial arable soil and above the deep rocky substrate (the bedrock). It is a layer of soil without contact with the atmosphere, composed predominantly of leached minerals, composed of iron, aluminum and other similar metals, as well as clay and accumulated humus.

The color of the subsoil is usually lighter than that of the surface, generally in combinations of brown and yellow, due to the low presence of organic materials, but usually also contains a significant presence of water, so the deepest roots of large trees reach this depth. Microorganisms and animals, however, do not usually have much presence in this layer, given that in the subsoil the oxygen concentration usually decreases noticeably.

The subsurface can become exposed to the atmosphere when large geological features occur or human economic activities drill into the ground, usually in search of mineral deposits. In these cases, however, wind erosion and runoff (rainwater movement) cause more severe effects on the soil and the possibility of contamination increases considerably. Even so, Subsoil contamination is a frequent problem, as toxic materials often leach from the surface to the depths.

On the other hand, From a legal point of view, the subsoil is the layer of the land where the public domain is considered established., that is, where individual property rights expire and the State becomes responsible for negotiating resources, for example, for mining, aquifer or oil exploitation. This is why the jurisprudence of the limits of the beginning of the subsoil (and, therefore, the end of the soil) is usually very important, since It constitutes a natural border between private and public land ownership.

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Continue with: Types of soil


  • “Underground” in Wikipedia.
  • “Underground” in the Dictionary of the Language of the Royal Spanish Academy.
  • “Subsoil Geology” at the National University of La Plata (Argentina).
  • “Subsoil (geology)” in The Encyclopaedia Britannica.