THE JOURNEY OF SEDIMENTS

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Status: Finished  |  Genre: Other  |  House: Booksie Classic
This article deals with the initial stages of sediments being eroded, transported and deposited. It tells us how the sediments are formed and get converted into sedimentary rocks through various diagenetic processes.

Submitted: September 14, 2012

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Submitted: September 14, 2012

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Whenever there is a volcanic eruption, the lava is spread over a larger area. This on solidification (cooling down and becoming a solid rock mass), forms igneous rocks. Theseare the huge igneous rock bodies that can be disintegrated by various natural agents like rains, wind etc.
From here, the journey of sediments starts!
The rocks are weathered and the transportation process starts which is generally carried out by the fluvial system (rivers and streams). These rivers carries these sediments and deposit them at the river bank where the gradient is low (Gradient can generally be called as Slope, for the beginners). The sediments are continuously brought by a river channel and keeps on accumulating on the river banks. The extent of deposition depends on various factors like:
•Gradient
•Velocity of river water
•Mass of sediments brought by the river
If the gradient is high, the river flows at a high velocity nd hence the sediments are not deposited there. On the other hand, they can be laid down at a place of low gradient. Now you can understand how the extent of deposition depends on mass of the sediments  brought!
There are some other terms you should know. Many a times we take the terms weathering, erosion and denudation to be the same thing. But geologically, all of them are quite different from each other.
Weathering referes to the process of fragmentation of rock. This happens because of FROST, TEMPERATURE (HEAT), BIOTURBATION etc. let us discuss them one by one. Due to frost, the water develops cracks in the rock because it penetrates into the rock and expand (when it gets frozen). The developed cracks, henceforth, degrades the rock. Heat (daily up and down of temperature) does the same thing, but by otherwise method, i.e. by rapidly expanding and contracting of the rocks. You can understand as to why the temperature varies during day and night and how the rocks would have been transformed! Now, comes the bioturbation. Bio means life and Turbation means a kind of intereference. So, when plants grow over an area, they spread their roots. If they found no or less area, they start penetrating their roots into the rocks. This causes their degradation and they got converted to loose sediments after being weathered.
Erosion is entirely different. It happens when some amount of loose sediments are washed over a surface. If a complete sheet of soil is washed away, may be due to water or wind, it is known as sheet erosion. It occurs in the areas of high gradient. Gully erosion occurs when water makes gullies all over the surface and takes away the material with it. It occurs on the areas, where gradient is low or the agent already has lot of eroded material with it.
Denudation, is the combinational effect of weathering and erosion.
But their journey does not ends here! They have to go various other processes before they get converted to sedimentary rocks. This is known as Diagenesis. But where are they going? Let’s ask them!
 
GLOSSARY
Bioturbation means the interference of micro-organisms or plants into the rock bodies which helps them to degrade and form loose sediments.
Erosion is the process of removal or washing away of the sediments over an area.
Gradient refers to the slope of the area. It is one of the relief features of an area.
Sediment is a naturally occurring material that is broken down by process of weathering and erosion, and is subsequently transported by the action of various geological agents like wind, water, gravity etc.
Weathering is the breaking down of rocks and it is in situ with the motion. (means no movement of sediments occur). They just gor degraded at their own position only.
 


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