Geology Site Account

Site name: Roydon Ferricrete

Grid reference: TL 4085 1021

Brief description of site:

A small but conspicuous boulder of ferricrete (60cm x 60cm x 50cm in size) protrudes from the grass opposite the war memorial not far from the church (Salter 1914).

The boulder was described by Salter as a Hertfordshire Puddingstone (Salter 1914).

Good building stone is rare in Essex and East Anglia but one exception is the rock ferricrete. In Ice Age gravels the movement of iron-rich groundwater has resulted in the formation of hard, solid masses of ferricrete which is an iron pan at the level of the water table. It is basically an iron-cemented gravel but it can be extremely hard and durable. Ferricrete has been used in the construction of several Essex churches.