Tuesday 8th April 2003
Monthly Meeting of the Essex Rock & Mineral Society
Big Jurassic Fish in a Big Jurassic Sea
by Dr David Martill

Notes: R Coleman

We extended a warm welcome to Dr David Martill, senior research fellow at the Department of Earth Sciences, Portsmouth University, for his first visit and talk to our Society.

David started by filling in the background to the original naming of species "Leedsicthys". The fossil remains were originally found by Mr Leeds during the 19 century in a clay pit owned by the London Brick Company (LBC). He explained that the LBC had developed brick making towards Oxford and Peterborough owing to several factors. The first being the vast requirement for bricks in the expansion and development of London, the development of the railways providing cheap transportation to the capital and primary to all this, the nature of the clay. The organic content of the clay from the middle and late Oxfordian was found specifically suitable for a "self sustaining" continuous firing system for brick making developed in the 19th century by an Austrian named Hoffman . This meant that no extra organic material needed to be added to the clay to "fire" the bricks, as required with London Clay, and hence cheaper to make!

The Victorian period seems to be the zenith of fossil collecting from the Oxford Clay. One reason, was that the clay was excavated by hand and it wasn't until the turn of the twentieth century that excavation became mechanized. More simply put, people are more discerning than machines!

David went on to explain the discovery and recovery of a specimen of Leedsichtys found in the Peterborough Member (named by David) of the Oxford Clay in a quarry in near Peterborough. There is a full account in the following link and a repeat of most of the lecture with pictures. http://www.nerc.ac.uk/publications/documents/Abigfish.pdf   Do follow this link, it is an excellent quality article!

The document is in a "pdf" file and naturally you need the Adobe reader (if you haven't got it, you can download for free, yawns loudly, "do I have to tell you were from?"). I find it wise to save the pdf file and read off-line. You will have to use the zoom function of the reader to enlarge the print and scroll around a bit. Have fun!

Fossils on display at the Meeting:

Only one but ........