Bedfordshire
Geology
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Bedfordshire Geology
Soils
“Every soil and every mixture of soil commonly seen on high land in the United Kingdoms may be found in this county, from the strongest clay to the lightest sand” said Thomas Batchelor in his General View of Agriculture of Bedfordshire (1808). And, what was true then is still true today, Bedfordshire has a wide variety of soils due to the different geological strata which outcrop over the county. To find out much more about soils in the county visit the National Soil Resources Institute website and use the interactive Soilscapes Viewer.
Some rocks found in Bedfordshire
- Chalk is the youngest of the Bedfordshire rocks (it was laid down about 70 million years ago) and is found in the south of the county. During the Ice Age - which ended about 10,000 years ago - great glaciers swept across the county and eroded away parts of the chalk leaving behind debris of clay, sand and gravel.
- Gault clay was laid down about 100 million years ago by rivers heavy in silt draining into coastal waters. Totternhoe has a thick layer of gault clay up to 230ft thick.
- The Lower Greensand was formed some 120 million years ago at the bottom of a shallow sea. Within the Lower Greensand can be found Fuller’s Earth which is formed as a result of volcanic explosion and the glass sands of the Leighton Buzzard area. The Lower Greensand also contains coprolites commonly, although incorrectly, known as “dinosaur dung” which were extracted for phosphates in the 1900s.
- Kimmeridge Clay was probably originally laid down over much of Bedfordshire but was largely removed by the pre-greensand erosion. An exposure was found in Ampthill.
- Ampthill Clay was deposited about 155 million years ago. It is also known as Corallian clay because in some areas of the country deposits of this date contain the remains of corals.
- Oxford Clay was formed at the bottom of a relatively shallow warm sea about 160 million years ago. It is this clay that is used to make bricks in Bedfordshire. Oxford clay extends over the greater part of north Bedfordshire, north of the Greensand Ridge.
- Cornbrash, was laid down in the middle Jurassic period up to 180 million years ago. It received its name because it gave rise to a stony or brash soil favourable to the growing of corn. At one time it was known locally as Bedford limestone and was quarried for building stone and for lime-burning. The Cornbrash outcrop is confined to the north-west of Bedfordshire.
Table of Geological Formations in Bedfordshire
| Recent |
Aluvium Valley Gravel |
| Pleistocene |
Brickearth River drift Glacial gravel and sand Boulder clay (with chalk erratics) Clay-with-flints |
| Eocene | Reading Beds |
| Upper Cretaceous |
Upper chalk Middle chalk Lower chalk Upper greensand Gault clay |
| Lower Cretaceous | Lower greensand |
| Upper Jurassic |
Kimeridge clay Ampthill clay Oxford clay with Kellaways rock |
| Lower Jurassic |
Great Oolite clay Great Oolite limestone Upper Estuarine series |
Bedfordshire Geology, by Bedfordshire Libraries, 2008
Page last updated: 15th July 2008
