Woburn Sands

The Lower Greensand forms a prominent ridge across Bedfordshire and has long been a source of sand.  The sands contain iron and are often stained yellow, orange or brown.  The purer sands are white.  Some layers are cemented with iron to form nodules and sandstone.

The sands were formed at the bottom of a shallow sea during the Lower Cretaceous period 120 million years ago.  Although the sands are poor in fossils they do contain signs of formed life.  They show disturbances caused by the digging and burrowing of marine organisms.  This is called bioturbation.  The remains of the creatures that formed the burrows are not preserved, they were dissolved away by water in the sands.  The sands also show cross bedding formed by the flow of water in the ancient sea.

Within the sands are found layers of fuller’s earth. This material was used to extract the grease from sheep’s wool, a process called fulling, hence the name.  Fuller’s earth is now used for a variety of chemical processes.  The seams of fuller’s earth are the product of a volcanic explosion.  Ash produced by the eruption settled in the shallow waters to produce the fuller’s earth layers.

At the base of the sands is a module bed, it contains fossils derived from earlier Jurassic rocks.  These fossils have been weathered out of the original layer of rock containing them, often the Kimmeridge or Oxford Clays, and into the sea.  As they rolled on the sea floor they became very smooth.  The nodules used to be quarried as a source of phosphate, this was once a flourishing industry.

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