Sedimentary rocks

Sedimentary rock is formed by compaction and lithification of weathered material of existing rocks. Sedimentary rocks are formed on or near the Earth’s surface, while metamorphic and igneous rocks are formed deep within the Earth. Erosion, weathering, dissolution, precipitation, and lithification is the most important process of making sedimentary rocks.

Erosion and weathering have the effects of wind and rain, which break down rocks into smaller pieces. Erosion and weathering transform boulders and even mountains into sediments, such as sand or mud. A dissolution is a form of weathering—chemical weathering. With this process, water that is slightly acidic slowly wears away a stone. These three processes create the raw materials for new, sedimentary rocks.

New rocks or minerals build through precipitation and lithification. For example, as a lake dries up over many thousands of years, it leaves behind mineral deposits; this is what happened in California’s Death Valley. Finally, lithification is the process by which clay, sand, and other sediments on the bottom of the ocean or other bodies of water are slowly compacted into rocks from the weight of overlying sediments.

Uses of Sedimentary Rocks 

Useful Sedimentary Rocks 

Many sedimentary rocks are useful For example, limestone is often used for building. Famous churches, such as Notre Dame in Paris, France, are made from limestone. Limestone can be heated and ground into cement. Coal is a sedimentary rock that is the mode of plants. When plants waste away, they become sediment. Pressure changes the sediment into cool. At one time buildings all over the world were heated by coal. People in ancient times used a sedimentary rock called flint to make tools. They also rubbed together pieces of flint to start a fire.

The Importance of Sedimentary Rocks 

Sedimentary rocks are also important to scientists. Scientists can study sedimentary rocks to see the layers of sediment that formed them. Studying the rock layers helps scientists discover how Earth formed and how much it has changed over the years. Sedimentary rocks also hold clues to how old Earth really is. Fossils trapped in these rocks tell scientists which creatures lived on Earth millions of years ago. Scientists can also study sedimentary rocks from different parts of the world to see what Earth looked like long ago. The rock cycle has helped shape Earth for millions of years. Being vital to the rock cycle, sedimentary rocks are necessary within the shaping of Earth’s surface. while not sedimentary rocks, Earth would be a really totally different place.

Types of Sedimentary rocks

there are 4 major types of sedimentary rocks: 

  1. Clastic Sedimentary Rocks
  2. Chemical Sedimentary Rocks
  3. Biochemical / Organic Sedimentary Rocks 

Clastic Sedimentary Rocks

The formation of a clastic sediment and sedimentary rocks involves four processes:   Weathering – solid rock break into smaller pieces or dissolved ions by physical and chemical weathering.Erosion – erosion begins the transportation process by moving the weathered products from their original location.Deposition –  Sediment is deposited when the velocity of the transporting medium becomes too low and deposit sediments.Lithification (Diagenesis) – Lithification is the process that turns sediment into rock by compaction. Compaction occurs as the weight of the overlying material increases.  Transported water carries mineral components in the solution and this causes cementation, which will then start to bind the particles together.
such as breccia, conglomerate, sandstone, siltstone, and shale are formed from mechanical weathering debris.

Chemical Sedimentary Rocks

Due to weathering, ions are dissolved in water and carried by the streams or groundwater. when these dissolved ions concentration is so high and water evaporates then ions recombine by chemical precipitation and form chemical sedimentary rocks.

such as rock salt, iron ore, chert, flint, some dolomites, and some limestones, form when dissolved materials precipitate from solution.

Biochemical Sedimentary Rocks

Biochemical and Organic sediments and sedimentary rocks are those derived from living organisms.  When the organism dies, the remains accumulated and become sediment or sedimentary rock.

 such as chalk, coal, diatomite, some dolomites, and some limestones, form from the accumulation of plant or animal debris.

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