Open Eye: On-line link to a mountain in Spain

Rosanne Jacks reports on a field trip with a difference

The words "I met him on the Internet" arouse suspicion in all who hear them. In this case, however, a relationship which started on the OU's First Class conferencing system gave rise to a meeting of students and tutors, both educational and enjoyable.

Linda Fowler, tutor of the OU's S103 Science Foundation Course at the Plymouth Study Centre and head of the South West Branch of the OU Geological Society (OUGS), first met Matthew Harffy on-line in May.

Having been an OU student herself, she took to heart Matthew's struggles with S103. During their correspondence, she learnt that he worked in the geology department of Madrid's National History Museum and he learned that her Society was planning a trip to Spain.

And so the idea was born. Matthew would arrange a field trip headed by his colleague, Dr Javier Garca Guinea, an eminent mineralogist specializing in thermolumine scence.

This is a new field which relates to the measurement of radioactivity and he is one of the few experts in Spain. The group also included Jan Ashton-Jones of the Society; Mary Maeso, studying S103; Luis Alonso, who had studied S102 (the previous version of S103); I am studying S267, How the Earth Works.

We met at the castle of Manzanares el Real just north-east of Madrid. Dr Garca Guinea arrived in a beaten-up jalopy, sending up clouds of dust, munching a doughnut and looking every bit the absent-minded professor and we were immediately on first-name terms.

We were in the Sierra de Guadarrama, north of Madrid. These mountains were formed about 350 million years ago; the highest peak is Pef dust, from which Javier was eager to begin the trip by showing us a bed of quartzite and smooth, layered, aluminium-rich mica schist and muscovite. Never mind that a busy main road cut right through the bed, and that the site was situated just after a blind curve!

With some trepidation, we parked on the side of the highway and Javier, oblivious of any danger, marched a terrified group of us up the slippery slopes. He was intense in his explanation of every feature, and by the time I found myself holding a shiny, cool piece of the layered stone I had forgotten my worries. And so, it seemed, had everyone else: Linda and Jan pulled out their hand lenses, Luis began snapping pictures of the deposits, Matthew was stuffing his pockets with specimens and Mary was taking notes.

Even so, I think we were all relieved when two policemen on motorcycles ordered us away. As I scuttled back into Luis's car, I overheard a relaxed Javier explaining that he was just showing "some English geologists" the rocks.

Before we left, he pointed out the limestone basin to the north. This was our next stop. Several wrong turns took us through sleepy Castilian villages, our curious caravan causing local heads to turn.

We finally arrived at the edge of a limestone cliff cut by a very deep fissure only a few years old: the tree-roots spanning parts of it were testimony to its young age. Javier explained that this fault, and several smaller ones, had probably opened up as a result of a series of small earthquakes. A great portion of the cliff had slipped into the valley, helped by underlying deposits of clay minerals.

We speculated that the "faulty" part we were standing on would probably suffer the same fate some time in the future.

We left the cliff and went for coffee. The walls of the cafe had superb examples of augengneiss or "toad's eyes" - a metamorphic rock rich in feldspar, quartz and garnet.

But nobody was as interested in the coffee as they were in the counter top: it was made of three different granites, two pinks from Galicia in the north-west of Spain and a local white stone.

Leaving the bar, we noticed a distinctive tile in the terrace floor. It contained a clot of pegmatite, an igneous intrusive rock which found its way into the granite, as veins, after the granite was formed. Width- wise cutting and polishing of the vein resulted in a beautiful ringed design.

We huddled on the floor and took our cameras but only after Javier had placed a rule beside it were we allowed to take our photographs.