There are three types of rocks on planet earth: sedimentary, igneous and metamorphic. Igneous rocks are made of magma, either on the surface of the earth or inside the crust. Metamorphic rocks are an outcome of existing rocks undergoing a transformation owing to changes in pressure and heat among other environmental conditions.
Sedimentary Rocks: Explained!
Sedimentary rocks are a result of accumulating sediments over a period of time. Different kinds of materials, including metal and minerals as well as organic matter, can accumulate together and form sediments. These sediments get deposited in a particular place, taking a hardened shape and form over a period of time. These rocks are called sedimentary rocks. Sedimentary rocks are of three types: clastic, chemical and organic.
Clastic sedimentary rocks are formed when materials dissolved in water precipitate and accumulate over time. Common examples of clastic sedimentary rocks are sandstone, conglomerate, siltstone, breccia and shale. Chemical sedimentary rocks are also formed as a result of the precipitation of the dissolved materials but it happens inorganically. When the dissolved materials in the liquid are far too saturated, they tend to inorganically precipitate from the solution. Common examples of chemical sedimentary rocks are iron ore, rock salt, dolomites, flint and limestone. Organic sedimentary rocks are formed due to the accumulation of animal and plant debris. Common examples of organic sedimentary rocks are coal, limestone and dolomite. It must be noted that dolomites and limestone are categories of rocks and not just a singular type of rock. Hence, some limestone or dolomites are organic while some are chemical sedimentary rocks.
Common Sedimentary Rocks
Coal is the most widely found sedimentary rock. It is formed primarily from debris of plants but also of animal fossils. Conglomerate is another common sedimentary rock. It is a clastic sedimentary rock formed. Most sedimentary rocks are soft and the various particles or pebbles, you could also call them granules, of the rock are bound together by some kind of cementing material. Sedimentary rocks are thus relatively fragile. Flint is a relatively hard sedimentary rock. Dolomite, Limestone and Iron Ore are some of the other common sedimentary rocks.
The Environment & Sedimentary Rocks
Sedimentary rocks are formed under the influence of the natural environment. They are vulnerable to erosion due to air or wind, water and movement of glaciers. They are also easily transported by water. The erosion and transport of sedimentary rocks lead to changes in shape, form and composition. Sedimentary rocks can lose their mass or gain mass when they are transported by water or are subjected to changes due to movement of glaciers.