Essex Rock & Mineral Society
Monthly Meeting, Tuesday 13 April 2004
A New Look at Tectonic Driving Forces by Bob Maurer.
This is one of those lucky occasions when an "IGNORAMUS" like me has no need to write notes on a subject he knows absolutely nothing about.
Thankfully, Bob has a website that says it all www.tectonic-forces.org A very enjoyable lecture with lots of visual props to explain the principles.
Members' finds on Display:
Bob Williams:
This month there was a table display entitled, "Are all these fossils dead?" Bob Williams had arranged a collection of crustacea from the fossil record and their modern counterparts still living.
The Neptunea contraria from Walton was there side by side with a modern Neptunea contraria Bob explained that this species still lives in warmer waters and that it had migrated south as the climate changed since its Walton days. Now for me the real conundrum is why contraria? Is or was there a Neptunea that spiralled the other way and looked identical? Bob say's this would be a different species in the truest sense. I'm still puzzled why the reverse spiral whilst other species go the other way. Having taken a quick look through the books on British Fossils and found no mention of other reverse spirals makes me even more curious. What evolutionary step caused this path? Do some little baby specimens spiral the other way but never make it to an adult, never find a mate? The interest is that the spiral is so mathematically pure that one thinks that there must be a genetic switch to this mirror image! Or what niche offers advantage to the reverse spiral? Temperature alone doesn't seem to offer the answer. Mostly it's down to feeding and sex!
Come to think of it, how do they breed. Bob's the zoologist so I'll ask him next month!
Doreen White:
Doreen,
one of our more active Lapidaries, brought along these three small stone
cats she has just made. The material looks like "red tiger-eye, lace
agate and snow flake obsidian" from left to right!
Text and Photographs © R Coleman 2004