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- In geology and particularly in sedimentology, a nodule is a small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition from the enclosing sediment or sedimentary rock.
en.wikipedia.org/wiki/Nodule_(geology)
In geology and particularly in sedimentology, a nodule is a small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition from the enclosing sediment or sedimentary rock. Examples include pyrite nodules in coal, a chert nodule in limestone, or a phosphorite nodule in marine shale.
Nodule, rounded mineral concretion that is distinct from, and may be separated from, the formation in which it occurs. Nodules commonly are elongate with a knobby irregular surface; they usually are oriented parallel to the bedding.
- The Editors of Encyclopaedia Britannica
For soil science students and soil survey practitioners who want more than a simple definition, this glossary offers additional information for a deeper understanding. A wide array of terms are included.
- O Horizon –
- A Horizon –
- E Horizon –
- B Horizon –
- C Horizon –
- R Horizon –
‘O’ is for organic. This layer is the uppermost layer of the soil rich in organic matter, such as the remains of plants and dead animals. Due to high organic content, this layer is typically black brown or dark brown. The O horizon is thin in some soil, thick in some others, or absent in the rest.
Found below the O horizon, it has a dark brown color as it contains the maximum organic matter of the soil. The A horizon or topsoil is thus also called the humus layer. The topsoil is the region of intense biological activity and has the most nutrients. Insects, earthworms, centipedes, bacteria, fungi, and other animals are found inside this layer...
This layer consists of nutrients leached from O and A horizons and is thus called the eluviations layer. Leaching of clay, minerals, and organic matter leavesthis layer with a high concentration of sand, slit particles, quartz, and other resistant materials. E horizon is absent in most soils but is more common in forested areas.
Mostly found below the topsoil is another layer called the subsoil or horizon B. It is lighter in color than the topsoil due to lower humus content. However, it is comparatively more rigid and compact than the topsoil. This layer has less organic content but is rich in minerals that are leached down from the topsoil. The subsoil is the region of de...
Also known as regolith or saprolite, it lies just below the subsoil. It is called the parent rock because all the upper layers developed from this layer. C horizon is devoid of any organic matter and is made of broken-up bedrocks, making it hard. Plantroots do not penetrate this layer. This layer is a transition between the inner layer of earth and...
Found beneath all the layers, it consists of un-weathered igneous, sedimentary, and metamorphic rocks. It is highly compact. Granite, basalt, quartzite, sandstone, and limestone make up the bedrock.
Nov 8, 2024 · This article covers the structure, composition, and classification of soils and how these factors affect soil’s role in the global ecosystem. In addition, the two most important phenomena that degrade soils, erosion and pollution, are discussed.
- Garrison Sposito
- Soil is the biologically active and porous medium that has developed in the uppermost layer of Earth’s crust. It serves as the reservoir of water a...
- The grain size of soil particles are categorized into three groups: clay, silt, and sand. Clay measures less than 0.002 mm (0.0008 inch) in diamete...
- The evolution of soils and their properties is called soil formation, and according to pedologists, five fundamental soil formation processes influ...
- Soils have a unique structural characteristic that distinguishes them from mere earth materials: a vertical sequence of layers produced by the comb...
Aug 11, 2022 · In some soils, the B horizon contains nodules or a layer of calcium carbonate. The subsoil is usually lighter in color than topsoil and often contains an accumulation of minerals.
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Jun 26, 2021 · Learning Objectives. To recognize the variety of sub-disciplines that exist within soil science. To define “soil”. To understand the primary soil forming factors and processes. To learn the concepts and methods used for identifying and describing soils (color, structure, texture)
