Alison Tasker, PhD Student

The micropalaeontology and geographical provenance of chalk tesserae used in Roman mosaics

Supervisors: Dr Mark Williams, Prof. David Siveter (University of Leicester); Dr Ian Wilkinson (BGS); Prof. Michael Fulford, Dr Samantha Cook (University of Reading).

Project Overview 

Alison Tasker
Alison Tasker

My project integrates geology, palaeontology and archaeology to determine the source of chalk tesserae used to construct mosaics in Roman Britain. Microfossils extracted from these small chalk 'cubes' can be used to date the rock and so identify its likely geographical provenance. Knowing where the chalk originated and where it ended up should provide information about the movement of mosaic materials around Britannia and shed light on trade and transportation in the Roman province. 

Rotalipora cushmani
Rotalipora cushmani / BGS MPK 14107

The microfossils that I work most closely with are foraminifera. Images of these taken with a camera and a scanning electron microscope (SEM) reveal their different morphologies (shape, size and other physical attributes). It is on the basis of these differences that species of foraminifera are identified. Species evolve over time, so differences in them and in the assemblages in which they are found can be used to date the source rock.

Hedbergella sp.
Hedbergella sp. / BGS MPK 14108

Some of the chalks are very hard and the microfossils they contain can best be identified from thin sections.

Camera and SEM images of foraminifera taken from thin sections appear on this page.

The need for more and better information on the geographical origin of mosaic materials has led to a growing recognition of the contribution that geology can bring to archaeology in the field of provenance studies. In recent years, the provenance of tesserae has been investigated using microfacies, petrological and geochemical analyses. Microfossil analysis is proving to be another powerful tool in the archaeologist's armoury and should contribute much to our understanding of the use of raw materials in mosaic manufacture. 

Arenobulimina sp.
Arenobulimina sp. / BGS MPK 14109


  • Wilkinson IP, Tasker A, Gouldwell A, Williams M, Edgeworth M, Zalasiewicz J and Christie N (2010). Micropalaeontology reveals the source of building materials for a defensive earthwork (English Civil War?) at Wallingford Castle, Oxfordshire. Journal of Micropalaeontology 29, 87-92.
  • Tasker A, Wilkinson IP, Fulford MG and Williams M (2011). Provenance of chalk tesserae from Brading Roman Villa, Isle of Wight, UK. Proceedings of the Geologists' Association 122, 933-937.
  • Tasker A, Wilkinson IP, Williams M, Morris M, Cooper NJ and Fulford, MG. (2013). Provenance of Chalk Tesserae from a Roman Town House in Vine Street, Leicester. Britannia. In press.

Oral presentations

  • Mosaics and microfossils (Science@Silchester, Silchester, July 2009, 2011).
  • Mosaics and microfossils (WEA, Leicester, March 2011).
  • Mosaics and microfossils (ASPRoM Summer Symposium, Hull, 2012)

Poster presentation

  • UKAS (UK Archaeological Sciences) Conference, September 2009.

Conference joint organiser

  • Progressive Palaeontology Conference held at the University of Leicester, July 2011.
Progressive Palaeontology 2011 Group Photo
Progressive Palaeontology 2011 Group Photo

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