The Chalk of Norwich

Post date: May 30, 2015 7:47:52 PM

A chalk sampling and microscopy event - May/June 2015

The Chalk of Norwich is one of the classic areas for Cretaceous geology. It is palaeontologically rich and includes some of the highest Cretaceous strata to be found in Britain. Sadly, many of the sites available in the C19th and early C20th cannot now be accessed. A recent Geological Society of Norfolk (GSN) event saw 20 people exploring the microscopic fossils from two disused chalk pits, under the tuition of Prof Andy Gale (Portsmouth).

The idea was to:

• • promote chalk palaeontology skills and interest among GSN members;

  • disseminate information about research into the Chalk of Norwich (e.g. Wood 1988; Pitchford 1990; Gale & Sørensen 2014);

  • promote geological conservation work by the Norfolk County Geosites Group.

Chalk sampling day (23^rd May)

The Chalk geology of Cringleford and Keswick belongs to the Campanian Stage, dated c.75 million years ago, and has horizons rich in fossils. Ongoing work by Andy here has recently identified species new to science, including 15 from Cringleford alone. Using published site logs, we took samples from designated horizons by reference to flint marker bands.

Chalk microscopy day school (6^th June)

Thanks to the lab facilities at the Environmental Sciences dept, University of East Anglia, we examined microscopic residues from the two pits. Macrofossils are scarce at these sites, so small (meso) fossils are important if we are to understand details of palaeo-ecology. Comparative samples from the Gault of Folkestone and the Campanian Chalk of Ivö Klack in Sweden were also available, and provided an interesting contrast: the Gault samples were from a muddy seabed deposit of Albian (Lower Cretaceous) age, and the Swedish were from sediment deposited between boulders on a rocky coastline of roughly similar age to Norwich. Andy provided specimen identification handouts and other reference guides as well as a Powerpoint introduction. UEA provided the binocular microscopes, brushes and petri dishes. The result was a fascinating glimpse into the beautiful world of chalk mesofossils - it was difficult to believe we were looking at specimens 75 million years old. Exquisitely formed and preserved brachiopod, bryozoan, echinoderm and ostracod fossils were abundant, with occasional barnacle plates, fish scales and teeth. A specimen of the newly-described barnacle Arcoscalpellum scaniensis Gale was found, and the lab technology allowed notable finds to be projected for all to see.