The soil stratification is the way in which the sediments of the soil accumulate on top of each other, in layers. Soil formation is a process that lasts millions of years, and in that time hundreds of thousands of layers of different materials have accumulated.
The rock or layered soils are composed of visible layers of sediment, which can measure from a few millimeters to several hundred meters thick. They are composed of a great variety of forms and materials.
The strata can be formed by layers of earth, rest of living beings, gases, water, mineral salts, lava, stone or volcanic fragments deposited one on another.
The stratification of the soil can be seen with the naked eye in some places, for example, the channels of millennial rivers. This stratification is so ancient that it has been transformed into rock.
Sedimentary rock was formed with layers of sediment over time. These layers of sediment create the pattern of visible bands or strata. These strata show the geological history of the environment in which the rock was formed.
For example, if there is a layer of clay followed by a layer of limestone, it is known that the environment was once a mud-covered environment before it became a lake or something similar.
Causes
The layers or strata are marked in view of the result of changes in the texture or composition of the material during its deposition.
This exposure of strata may also be due to pauses produced in the deposition of different materials, or to changes in their composition or temperature before the new strata covered them.
Another cause of the particular form that the profiles take, especially in the river channels, is the composition in particles, some finer and others thicker. The different colors originate in the different mineral compositions.
The water and the wind also intervene, doing a homogenization work of the trailing particles, classifying them according to their size, weight and shape. This is giving shape to stratification.
Characteristics of profiles and horizons
The strata are called"horizons"and the set of layers is called"profile" .
Each profile is composed of at least four horizons, listed below from top to bottom:
1- Washing horizon
Exposed to the erosion and washing of rain, it is composed of porous organic matter, living organisms and minerals.
Also made up of remains of leaves and branches, humus and fungi. In addition, it has some inorganic elements and its color is brownish.
At a deeper level it contains clays, iron oxides and moist organic matter.
2- Precipitation horizon
It has clays and presents reddish tones for its ferric compounds. It also contains traces of altered rock and organic material from the first profile.
3- Horizon subsoil
It consists of rocky material fragmented in different proportions, subjected to processes of weathering or decomposition of the rock into smaller parts, physically or chemically.
4- Horizon rock mother or original
It is a rocky material on which the soil is supported. It is composed of inorganic elements of volcanic, sedimentary and grains origin of petroleum.
It remains virtually unchanged, or unimpaired, over time.
References
- Ryan Hultzman. (2017). Stratification: Definition, Theory & Examples. 09/30/2017, from Study.com Website: study.com
- The Editors of Encyclopædia Britannica. (2017). Stratification. 30/09/2017, of Encyclopædia Britannica Website: britannica.com
- Editors. (2017). Stratification. 30/09/2017, of Science and Biology Website: cienciaybiologia.com
- IUSS Working Group WRB, 2015. World reference base for the Soil Resource 2014, Update 2015. International Soil Classification System for Soil Nomenclature and the Creation of Soil Map Legends. Reports on global soil resources 106. FAO, Rome.
- Editor. (2017). Sedimentary Structures. 03/10/2017, from Indiana Edu Website: indiana.edu