gcsescience.com                                       9                                       gcsescience.com


Sedimentary Rocks - Transport and Compaction.

What is Transportation?

Small pieces of weathered rock (called sediments) are
transported by rivers. This means that the rock pieces
are moved along as the river flows towards the sea.

During transportation, the sediments are sorted according to size.
The largest pieces tend to be deposited first. Sand is next to
settle out of the water. The smallest particles are mud or clay,
and these are moved furthest by the river and deposited last.

What is Compaction?

With the passing of time, the deposits of sediment get
thicker and thicker. The sediment underneath becomes
increasingly crushed by the weight of the new sediment which
is being deposited on it from above. This is called compaction.

It is this process of compaction
which eventually makes layers of sedimentary rock.
The process may take millions of years.
The largest rock pieces will produce conglomerate.
Sand will produce sandstone.
Mud or clay will produce mudstone or shale.

Younger sedimentary rocks are usually found on top of older rocks.
Rock layers generally get older the deeper down you go.

back      Links      Sedimentary Rocks      Revision Questions      next

gcsescience.com     The Periodic Table     Index     Rocks Quiz     gcsescience.com

Home      GCSE Chemistry      GCSE Physics

Copyright © 2015 gcsescience.com. All Rights Reserved.