Sedimentary rocks are classified as clastic, chemical, organic and sedimentary rocks.

The rocks in each group by a process completely different.

Clastic Sedimentary Rocks

Clastic sedimentary rocks are formed from sediment. The sediments are little bits and pieces of rock that settle out of air or water.

Weathering

All rocks are subject to the weather. Weathering is anything that breaks the rocks into pieces more small or sediment. This can happen by the forces of wind, rain, or moving and freezing water.

Deposition

The sediment formed from these actions have been to other places by wind, water and gravity. As these forces lose power in the sediments settle in air or water. As the solution takes place, the rock fragments are classified by size. The larger, heavier pieces settle first. Most small fragments to travel further and pay off the last out.

Erosion

The combination of erosion and sediment movement result is called erosion.

Lithification

Lithification is the change of sediment into rock. There are two processes involved in this change. They are the compaction and cementation.

It occurs after compaction of the sediments were deposited. The weight of the sediments squeezes the particles together. When more and more sediments are deposited on the top, the weight of the sediments below increases. The water-borne sediments so tight that most of the water is forced out.

Cementation occurs when dissolved minerals fill the spaces between sediment particles. They act as a glue liquid minerals or cement to bind the sediment together.

Clastic sedimentary rocks are further organized according to the size of the particles sediment.

Chemical sedimentary rocks

Chemical sedimentary rocks are not formed from sediments on the road are clastic sedimentary rocks. Instead, they are made by chemicals (elements) dissolved in water. Lakes, rivers, oceans, and groundwater have dissolved chemicals in elementary them.

There are three types of chemical sedimentary rocks. They are the evaporates, carbonates and silica sedimentary rocks.

Evaporate

Evaporites are formed when the body of water evaporates, leaving deposits of one or more chemicals. The white deposits on your sinks and faucets are the beginnings of this rock type.

Another example of evaporate sedimentary rocks can be found in your kitchen. Most table salt comes from Utah. The Great Salt Lake is the remnant of a vast inland sea that once covered much of the western United States. It is gradually decreasing in size due to evaporation. As the water evaporates the lake can no longer maintain the same amount of salt. The salt precipitates and is deposited in halite crystals.

This is the basic process for all evaporates. As water evaporates, the remaining water is saturated with elements. The water can not contain the elements of the solution and crystallize into solid form.

Carbonates

Carbonate sedimentary rocks are formed by chemical and biochemical processes. Limestones and dolomites are included in this group. They are composed primarily of two minerals, calcite and dolomite CaCO3 CaMg (CO3) 2

Siliceous rocks

The siliceous rocks are dominated by silica SiO2. Silica-secreting organisms like diatoms and radiolarians are responsible for training This type of rock.

Organic sedimentary rocks

Organic sedimentary rocks are composed of organic matter in the form of fragments of the plant. We usually think of this group of rocks as coal. Lignite is black and has a crumbly consistency. Bituminous coal can be dull to shiny black.

Geologists use simple classification system to organize the different types of rocks. The system is based on how the rock was formed. Variations in the process of forming qualities cause unique in the aspect of the rock. It is quite logical, so with a little practice, you can see how different conditions affect how the rock looks.

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