Sedimentary Rock Examples

Rocks are usually divided into three different categories: igneous, metamorphic, and sedimentary. While igneous and metamorphic rocks are abundant, most of the rocks on Earth are actually sedimentary.

These rocks are formed when tiny pieces of dirt, soil, rock, and organic matter like decaying animals or rotting plant refuse accumulate in one location and settle there. For this reason, sedimentary rock is known to contain plant and animal fossils.

In areas where there is a high level of plants and animals, fossil fuels develop beneath the layers of rock. These fuels include substances like oil, natural gas, and coal.

1. Sedimentary Basins

These basins, or areas of low land where water can accumulate from rivers, lakes, or even oceans, contain higher than average layers of sedimentary rock due to the constant addition of new particles carried by the water, mostly through erosion. Some of the specific types of basins found on Earth include rift basins, sag basins, foreland, basins, and fore-arc and back-arc basins.

2. Varieties

Sedimentary rock is broken up into different types, which include carbonate, clastic, coal, and chemically precipitated rocks. The carbonate rocks include several different kinds of limestone, chalk, and numerous other rocks which are composed of carbonate minerals. Clastic rocks are made up of smaller pieces of rock called clasts that have been cemented together through sedimentary processes, and include shale in all its forms, and many other types of rock. Coal is one type of sedimentary rock that is formed in the presence of organic matter like decaying plants or dead animals, forming over long periods of time under the right conditions. Chemically precipitated rocks like flint and gypsum, to name only a few, are formed when layers of sediment are left by water, and then the water evaporates, leaving only the minerals behind.

3. Other Types of Sedimentary Rock

There are other types of this rock besides the four main categories, many of which include shell beds or bone fragments that have been compacted and cemented into rock by the forces of extreme heat and pressure.