Always a difficult month with so many people on holiday, but our members still managed to turn out in force. Usually this is the opportunity for individual members to show or talk about their finds and experiences for the year.

However, on this occasion we were treated to a guest appearance by two representatives of a project, that is currently underway at Goresbrook Park. The initiative is to re-landscape the area with some imaginative features. Part of the programme is to try and instill the essence of the natural appearance of a 'Drumlin' and 'Boulder Field', both remnants of Ice Age activity, and one characteristic feature of the countryside in the North of England. Not surprisingly the concept of the idea came from the Yorkshire born artist commissioned for the project. (Didn't they do something similar on Salisbury plain a few thousand years ago? Long Barrows and a few stones dotted around!)

We were treated to a some wonderful slides of Drumlins and Boulder Fields to help us visualize the idea. The 'Goresbrook Park Initiative' was to involve local groups in this project, partly to help generate a feeling of community spirit and achievement in the locality. To this end they had arranged a coach trip to 'Devonian Sandstone' quarry in the West Country. The object was to select boulders in the range 30-50 tonnes plus and opportunity to visit the designer's studio. They had about ten seats remaining and there were no costs involved. The question we were asked was; whether the Society would become involved in the project and whether there were any takers for the trip?

Member's Displays

Bob Williams brought along a three display boards. One had a selection of class photographs depicting the (now collapsed) chalk arch on the Isle of White as mentioned by last month's speaker Ken Newman.

The other two display boards included pictures and text covering Bob's research work of the London Clay fauna from the Aveley Pit.

(Now some of us know Bob and others don't. Doesn't seem like much to prepare 3 boards all by yourself does it! Think again? Well done Bob.)

David Turner brought along his collection of 'Sponges' and 'Nautilus' from the Faringdon trip. (Fabulous Nautilus and not glued together like someone else's, because they broke it as it rolled around in the car!).

Ursula & Jon Deith had a wonderful display of Whale bone from the Naze, including an ear bone and one of the best Trilobite specimens I have ever seen from the Gilwern trip a few weeks ago. (Surprisingly, none of these were glued together!)

Doreen White put on an exhibition of stones and rock for us to guess where they came from. Amongst them was a small piece of Pink & Black Gneiss. The black bands were composed of mostly small flakes of mica (biotite 0.5 - 1mm) obscuring other dark minerals or mineral. The light coloured bands were a granular mix of clear to white quartz mixed with pink feldspar (presumed). This was a sample from Doreen's a recent trip to Scotland. She describes this as metamorphosed Torridonian sandstone. I presume the ascribed sandstone source was stated by the leader of the trip. Doreen assures me they were excellent and certainly made me wish I had been there, as they went to lengths to describe the geology and rocks.

Ron Frost brought in some pictures of Trace Fossils from a friend's patio/path. There were ripple mark features on most slabs. Some had what looked like tyre marks cutting across them and one had a distinct straight grove. Ron wanted to know if any of us could identify these? This set me thinking, as I had to learn something about trace fossils once. The groves, both single and multiple, are attributed as "tool marks" caused by some artifact being rolled or dragged along by current flow, often seen at the base of turbidite beds. They are also a good indicator of palaeocurrent flow if the rock is still in situ. On rare occasions the 'tool' causing the grove can sometimes be found at the end. Other classic marks are caused as the 'tool' skips or bounces along as it is transported by the current.

As for the tyre treads, it is probably easiest to split trace fossils into two categories, vertical and horizontal structures (plant roots aside). Ron's examples appeared to be exclusively in the horizontal plane. The implication is that these are either a feeding pattern, mode of locomotion or resting place of organisms that dwell on the surface or generate horizontal burrows. They include everything from Trilobites to Dinosaur tracks.

Trace fossils are grouped according to the assemblage of different traces found (both vertical and horizontal) and are considered facies dependent. The name given to this is ichnofacies. The pattern of a trace fossil does not necessarily characterize a particular species, but it is possible to interpret how they were generated and what might have caused them.

(If you wish to know more about Trace Fossils, the LINK at the bottom of this month's article is about the best I can come up with. It takes a short time to download! There are many other references but this is a good one to start with. All said it is not a substitute for field work and your own experience. If you can find the 'Beastie' at the end of a 'Trace' you have something very rare indeed!)

Interestingly, the ripple marks suggest a shallow marine/tidal origin (best guess) and their preservation imply they were buried very quickly. One possibility is that it is from either an estuary or delta environment. (Pity we don't have a location for the rock other than someone's patio! Ah well, off to the Garden Centre for a few slabs of Trace Fossils of my own, if lucky!)

AN APOLOGY: Photographs - it was the first outing with a new camera bought specifically to improve the quality of the pictures I record for the website - guess who don't know how to use it? ME!

Announcements: there were the field trip reports for Gilwern and last weekend's trip to Birch, with tea and sandwiches after back at Bob Burton's. (A trip I didn't want to miss but sadly other problems forced my absence!) Bob & Kitty are two of the nicest people you could wish to meet. Want to know anything about Lapidary, Bob is the man! Some would say looking at his workshop you wouldn't even try to start. How wrong, one of us looked at Bob's workshop many years ago and started as soon as he got home.)

It was also announced that our club member Eric Venables has recently suffered a heart attack and is away convalescing. ( I have met Eric & Betty on two occasions since July's meeting. The initial attack had occurred some time previous whilst they were away on holiday. We don't see Eric at meetings because his main interest is in Lapidary and it is only on rare occasions that we have a lecture on the subject. All said, we all wish Eric a full recovery.

Picture of the Month
by
Doreen White

The M stands for Marathon!
Four participants of the event refreshing on Melons, as if they hadn't had enough already!
Left to Right
Stuart Adams, Les Lanham, Roger Coleman, Alan Smart.

Essex Rock & Mineral Society at the Dagenham Town Show July 2002

(© R Coleman 16 August 2002)

(Printing: Document optimized for A4 format
with all margins set to 10mm)

Trace Fossil Link

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