Saturday, 20 April 2013

Mineral County Wildlife Sites

 Helen Baczkowska, Conservation Officer

Snettisham common pit north, credit Tim Holt-Wilson
Once exploited for sand, gravel, clay or peat, disused mineral workings are found across Norfolk, ranging from small, hand-dug workings to huge pits filled with water.  Many of them, no longer worked, offer fantastic habitats for wildlife.

In the 1980s about 60 former mineral sites across Norfolk were surveyed and notified as County Wildlife Sites; habitats found included fragments of lowland heath, acid grassland, secondary woodland and open water.  By 2012, it was evident that many records for these sites were out of date and that re-surveys were essential to ensure the County Wildlife Site register was accurate.

Funding for survey work was supplied by Norfolk County Council and the Norfolk Biodiversity Partnership. Botanist, Chris Roberts set to work on a list of sites in need of survey.  As well as surveying plants and habitats, NWT worked with entomologists from the Norfolk and Norwich Naturalists Society to investigate invertebrates on some of the old mineral workings.  Abandoned workings often contain bare soil and heathland plants, which can provide a warm, rich habitat for ants, spiders and other insect life.

A third part of the investigations was to join forces with Norfolk’s keen amateur geologists; in a county like Norfolk, where there are few rocks in evidence, mineral workings often expose interesting geology otherwise well concealed beneath soil and vegetation.

By the end of last summer, 15 sites had been visited, with two new sites being added to the County Wildlife Site register. Perhaps the most interesting of the sites are those that have naturally reverted to heathland with heather and gorse, as well as those vital patches of bare soil. These habitats require careful management to ensure they are retained and over the coming months, NWT will be working with land owners to safeguard the future of these vulnerable habitats.

Snettisham Common, CWS 476 – a case study
Yellow meadow ant, Alan Price
Originally surveyed in 1984, the 2012 re-survey revealed extensive areas of secondary woodland, with a large, disused sandstone pit and fragments of lowland heath.

Geologist, Tim Holt-Wilson produced the report. The cliff exposes the Sandringham Formation of Lower Cretaceous, meaning it was laid down in a warm ocean around 100 million years ago. This is overlain by sands, clay and clay ironstone of the Dersingham Formation. A notable feature of the site is the faults, or cracks, which may be associated with the effects of glaciers or peri-glacial soil conditions.

One exciting find at the site was what is believed to be the first record in Norfolk for a rare, heathland pirate spider Ero aphana. A pirate spider is able to enter the webs of other spiders undetected and attack them. Other invertebrates found on the Common included the yellow meadow ant, Lasius flavus and the ruby-tailed wasp, Chrysis ignite, burrowing in the exposed sandstone. 

Snettisham Common is managed by Snettisham Parish Council and following advice from all the experts involved, NWT is helping them to work with the West Norfolk Conservation Volunteers and developing a management plan to enhance both the heathland and the exposed sandstone quarry.


  1. There's a little more information about our joint biodiversity / geodiversity work undertaken in north-east Norfolk in 2011 at

  2. Thanks Tim, that's a really useful link