Dr Hilary Downes wasted no time in getting into this talk. One of her first slides was of an outline map of Europe covered with broad red and blue areas representing the differing velocities of the upper and lower mantle of the Earth. My imagination ran riot with thoughts of rivers of molten mantle material rushing around many kilometers beneath our feet. When the penny dropped, it was the seismic velocity that was being talked about.

Hilary concentrated on how various examples of ultramafic rocks had risen to the surface and the definition of these types according to the quantity of pyroxyene minerals they contained. It struck me as funny that most had classifications with names of German origin like; Harzburgite, Wehrlite and Lherzolite except for Dunite, a name derived from its location of Mount Dun in New Zealand. It appears that most of these rocks where found as xenoliths in larva erupted from various volcanoes. There was a lovely picture of several cinder cone volcanoes, and an example of what looked like a weathered ovoid chunk sitting in the ash which turned out to be Olivine rich when broken. Another commonly found mineral was Garnet. The evidence pointed to these rocks having been raised from depths in the order of 70km plus, (because of the minerals they contained having been formed at high temperature/pressure), and making their way rapidly to the surface (substantially unaltered) through volcanic activity.

G.R. Ward Collection 51, OLIVINE nodule containing enstatite and chrome- diopside, in basaltic lava: Faja, Fayal, Azores. Collected by Dr R.W.D. Elewell, Summer 1967 ; acquired October 1967.

Graham brought this one in for us to look at. I've not seen many except in books and museums. I even got to pick it up!. Yippee! Geology is a hands on subject!

We were blitzed with a kaleidoscope of a few thin section pictures of the varying rock types. Views were in both plain light and through crossed polars. Hilary pointed out some of the salient petrological concepts relating to these rocks.

Perhaps quite amazing, was that mantle rocks are known to outcrop on the Earth's surface. Hilary concentrated on two locations. One was the Lherz Massif in France. On closer examination, these rocks showed bedding planes, with separation by thin vein like structures of felsic minerals (I think she said, but can't remember). Fold structures were also evident, plus also a high degree of brecciation of rocks. A total nightmare to explain and Hilary avoided the attempt, although she did hint that this outcrop appears to be on the boundary of two microplates. Another point is that the massif appears to have reached the surface by tectonic proposes other than volcanism.

The other outcrop of mantle rocks was that found within the cratonic areas such as the famous outcrop of Kimberlites in South Africa. She discussed some of the mineral assemblages that you could expect including diamonds. To me, the most thought provoking aspect was the carrot shape of the Kimberlite pipes. She said that they seem to have branched off and up from a dyke like feed from below. In some localities you could get two carrots side by side. ("I know the reason; carrot fly causes club root!"  "Thank you Mr Digwell"!)

Dr Hilary Jones concluded her talk with a short promotion of the Earth Sciences and Distance Learning Packages being offered by Birkbeck College. She brought along a few promotional CD's and other literature for those of us who may be interested. It appears that the courses are targeted at mature students who cannot do a full time degree and have to study in their spare time. (Wonderful!)

I've been through the CD and suspect that this the future. I do have reservations though and can honestly say that I prefer books, but I can hear you say; "Why not print it out"? On another point, they expect all your written work to be submitted in your own hand writing! No typed submissions! On a technical point there are two movie files of rotating thin sections in plane light and in crossed polars. They could have done better, in full screen they look too granular. It is not a substitute for looking down a microscope for yourself. I hope they back up all this computer style learning with plenty of hands on work.

Anyhow, check it out! Their web address is http:www.bbk.ac.uk/es. It may be just up your street?

Can you really learn from computers and websites? Hope so, I've just splashed out on a French learning programme for when I get the chance to have a look at the Lherz Massif face to face. Yes, I liked the talk!

Oh dear, just surfed around and found massif amounts about Lherz, looks like I'll have to buy the German learning package too.

I really ought to stick to British Geology.

(RC 14/10/2001)

Other Notices:

Stuart Adams announced that the Society will have space at the Collier Row show he organizes on behalf of the Society. He asked that we start planning a display ready for the Show.

Stuart also asked that we start submitting poster designs for the 2003 show now! (Nothing wrong with forward planning.)

Many thanks to Sandra & Bob Blackburn who brought along their recent finds from the Norfolk Coast Trip of 29/30 September.

Ron Flack was passing aound a Flint Tool he found on the Norfolk Trip. You could quite clearly see that it had been worked by man, especially along the cutting edge. (Sorry, I forgot to photograph it!)

Thanks to Bob Welham for supplying photographs which will be featured on this site shortly.

On a personal note, I'm pleased that members are just beginning to get the idea of feeding me reports and other relevant information for inclusion on our website. More please! (RC 14/10/01)

Previous reports on meetings: September August, July, June, May,