London's Rocks - An Overview
London's geology is made of a number of different types of rocks, most of which are sedimentary. Many of the rocks that are here today came from the Tertiary period, such as the famous blue clay, which can be found near the river Thames and around most other parts of London. Other rocks, such as the hard mudstone, or red sandstone are form the Silurian period. Also there are ones which are from later periods, like the Quaternary period. These are rocks such as till or gravel.
London's geology is quite complex as there is a great variation in the rocks, and depending on where you are in London, the rocks that lie beneath your feet can be completely different. This is especially clear between the two sides of the river Thames, where one side is all chalk, and the other all clay.
There are some terms which will be discussed in this website which you may not be familiar with, so here is a glossary of terms:
Till or glacial till is unsorted glacial sediment, which was formed in the Quaternary Period
Alluvium is loose, soil or sediment, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.
Tertiary Period is about 1.6 to 66.4 million years old.
Quaternary Period is about 2 million years ago to now.
Fossils are the remains of animals perserved in rocks or superficial deposits
London's geology is quite complex as there is a great variation in the rocks, and depending on where you are in London, the rocks that lie beneath your feet can be completely different. This is especially clear between the two sides of the river Thames, where one side is all chalk, and the other all clay.
There are some terms which will be discussed in this website which you may not be familiar with, so here is a glossary of terms:
Till or glacial till is unsorted glacial sediment, which was formed in the Quaternary Period
Alluvium is loose, soil or sediment, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.
Tertiary Period is about 1.6 to 66.4 million years old.
Quaternary Period is about 2 million years ago to now.
Fossils are the remains of animals perserved in rocks or superficial deposits
This map shows the different types of rocks in different areas of London. For example around the River Thames there is a vast amount of London clay, which was deposited around the Tertiary period. To find out more about the types of rocks in London look at the next pages.