Cornbrash

The Cornbrash is a Middle Jurassic limestone, which often has an orange colour due to iron staining.  It is rich in a wide variety of fossil sea creatures.  An increase in sea level in the middle Jurassic resulted in a shallow sea being formed.  It was at the bottom of this sea that the Cornbrash was formed.  Prior to this the habitats of the area had been shallow lagoons, deltas and even areas of fresh water.

The Cornbrash is only a thin band of limestone but it can be divided into two layers based on the ammonites it contains.  The lower layer contains an ammonite called Clydoniceras; the upper layer, an ammonite called Macrocephalites.  These layers can be subdivided further stillby means of the fossil brachiopod shells they contain.

After the Cornbrash the Kelloways beds were deposited.  These were followed by the Oxford Clay.  Throughout this time the sea was gradually becoming deeper.

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