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Sequence (geology)

earth science Maturity 7-9 Next article →

Geologists study the history of our Earth. They look at many layers of rock. These layers are called strata. Sometimes, these layers form a special group. This group is called a sequence. A sequence is a single unit of rock. It helps scientists understand the ground.

A sequence works in a very specific way. It is a group of rock layers. These layers must be genetically related. This means they formed in a similar way. The layers are also relatively conformable. This means they mostly fit together well. A sequence has a clear top and bottom.

These edges are very important to know. The top and bottom are called unconformities. An unconformity is a gap in the rock. It is a surface that marks the edge. These edges can also be correlative surfaces. They show where one group ends. They show where a new group starts.

There are different kinds of these rock groups. Some are called type 1 sequences. Other groups are called type 2 sequences. Scientists also study parasequences. Do not let the name fool you. Parasequences are not just smaller sequences. They are a different idea entirely.

Learning about these groups is a big job. This study is called sequence stratigraphy. It is a part of the science of geology. Scientists use it to map the Earth. They look at how the layers fit. This helps them see how things changed. It is a way to read the ground.

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