The three main types of rock are:
Sedimentary rocks are formed by joining many broken remains of other rocks together. Some examples of sedimentary rocks are conglomerate, mudstone and limestone.
As bits of minerals settle into layers over thousands of years, the weight of water and the layers of sediment above press down and cement the minerals into sedimentary rock
1. Large rocks break up into smaller pieces (sediment) – This process is weathering
2. The pieces of broken rock are transported by natural forces, such as wind and water. – This process is transportation
3. The pieces then settle in layers at the bottom of the ocean – This is deposition
4. The weight of the water and layers of sediment above squash the sediment below – This process is known as compaction
5. Sedimentary rock is formed as the sediment layers stick together – This process is called cementation
Here is the order of the whole process to form sedimentary rocks:
|1) Weathering||2) Transportation||3) Deposition||4) Compaction||5) Cementation|
This is what sedimentary rock can look like:
You can see the visible layers of different colours and textures, which shows the different types of sediment. The surface of the rock may be rough or smooth, depending on the type of sediment that formed it.
Also, sedimentary rocks may contain fossils because dead organisms settle between the sediment layers as it builds up.