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What are sedimentary rocks?
They are one of the three major groups of rocks that make up the Earth's lithosphere.
These are formed near the surface through the accumulation of sediments from other rocks, the remains of living beings or the precipitation of chemical substances dissolved in an aqueous solution.
Sedimentary rocks can be classified according to their origin:
Biochemical
Formed from the remains of living beings or organic substances, resulting from their activity, which accumulate, causing their compaction and cementation. Good examples of biogenic sedimentary rocks are coal, conchiferous limestone.
Clastic
Formed from sediments of other rocks. These debris are formed through the exposure of the rock to weathering and erosion agents, which end up altering it physically and chemically.
Chemical
Formed through the precipitation of minerals dissolved in water. The water, in turn, evaporates, leaving behind the minerals, which eventually crystallize to form sedimentary rock. Some of these rocks are rock salt, gypsum and chemical limestone.
The sediments
Debris formed by weathering and erosion agents is transported by wind and water to coastal areas, in most cases.
Normally, these are deposited in sedimentary basins, characterized by the low energy intensity of water agitation. Under these conditions, diagenesis is favoured, which comprises compaction and cementation, and leads to the formation of a consolidated sedimentary rock.
Rocks such as sandstone, claystone and conglomerate fall into this category.
Rocky sediments can have different shapes and sizes, which vary according to the distance traveled in their transport.
Did you know
Fossils are preserved in sedimentary rocks.
