How are Sedimentary Rocks formed?
Sedimentary rocks are formed by the deposition and subsequent cementation on the material at the Earth’s surface within the bodies of water. These rocks are formed in four ways:
- Deposition of weathered remains of other rocks
- Accumulation and the consolidation of sediments
- Deposition of the results of biogenic activity
- Precipitation from solution.
What is Sedimentation?
Sedimentation is the combined name for all the processes that cause organic and mineral particles to get settle. The particle that helps in forming the sedimentary rock is called sediment. This sediment is formed with the help of erosion and weathering from the source area and which is then transported to the deposition place by the wind, water, ice and glaciers which are agents of denudation.
The best way to examine the rock type is to check the sediment grain size and variation. Its texture refers to the features and arrangements of the grain in such sediments. Its structure is present in rock beds and under surfaces which help in recording the palaeocurrents and has deposited in the rocks. It covers the continent of the earth’s crust, but the total contribution of these rocks is estimated to be by 8% of the total volume of the crust.
Some common sedimentary rocks are:
These rocks cover 75% of the total earth’s surface.
Types of Sedimentary Rocks
The sedimentary rocks are classified into three different types: Organic, Clastic and Chemical Sedimentary Rocks.
Organic Sedimentary Rocks
This rock type mainly comprises coal and limestones which is formed due to accumulation and deposition of dead plants and animals in rock layers.
Clastic Sedimentary Rocks
This type of rock is formed when rock layers are formed due to the mechanical weathering of different rock types.
Chemical Sedimentary Rocks
This rock type is formed when there is a chemical reaction between minerals, present in rock forms cools down as precipitate and converts to rock form over a period of time.
Check out the video below for more information on sedimentary, igneous and metamorphic rocks.
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Uses of Sedimentary Rocks
The use of sedimentary rock can be found in most buildings and monuments. Some uses of this type of rock are provided below.
- Limestone is used to make cement.
- Limestone and sandstone are used for building stones
- Quartz is a type of sedimentary rock which is used to make glass.
- Rock gypsum is used to make plaster.
Natural gas, oil, coal, and uranium, and other energy resources are formed in and come from sedimentary rocks.
Interesting Facts about Sedimentary Rock
Sedimentary rocks are formed by sediment that is deposited over time. Some sedimentary rock facts are provided below.
- Flint is a hard, sedimentary form of the mineral quartz.
- Sedimentary rocks cover most of the Earth’s rocky surface, but they only make up a very small percentage of the planet’s crust.
- They often contains fossils of plants and animals millions of years old.
- Limestone is often made from the fossilized remains of ocean life that died millions of years ago.
- These rocks form layers called strata which can often be seen in exposed cliffs.
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