Humberside Geologist no 13

Some Thoughts on the Millennium

By Cyril Dutton

WHEN ASKED TO WRITE for a special Millennium Edition one naturally considers the fact that 2 000 years have passed since Jesus was born. And then one considers the connection it has with geology. Not much is the first impression. Most geological societies began in the last century when the main centre of interest was the area local to the society. Today our thoughts have expanded not only to include the whole country, not even the entire Earth, but even our Moon. Geology was the basis of those trips by Apollo to the Moon. And as a result, the full geological history of the Moon has been established.

Our investigations have expanded also in other ways: Modern equipment can scan a piece of rock and printout its composition. This will include the trace elements so that one can be certain of the origination of that piece of rock.

Man is an intrinsic explorer. Man has visited our Moon, years ago. And now a new generation of un-manned exploration is in place to explore some of our planets and their moons with advanced methods. Already men are considering how to determine if there is, or ever has been, any life on Europa, one of Jupiter's moons. Why Europa? Well, recent research has been devoted to microscopic life. It has been shown that this is present everywhere there is water; and it is believed that water exists on Europa.

Now, having analysed Earth rocks, Moon rocks, Mars rocks, as well as the chemical composition of our Sun, we can use recently developed "telescopes" to determine the composition of other Suns in our Galaxy. And even ponder that one day man will reach some of our own planets.

So the concept and use of geology has grown by leaps and bounds. But was there no geology 2 000 years ago? Well, not as we know it. Yet the Romans were experienced with metallurgy. In any respectable museum you will find a sketch map showing the places gold, silver, copper, lead and other metals were mined throughout the whole Roman Empire. There was much business traffic between them. Romans were also very informed about the places gems were found. Of course, they inherited the skills of minting coins from the Greeks.

Without doubt, the Romans were expert in road building. This was related with their expertise in organizing and running their armies. They also had elaborate public baths: hot, warm, and cold. And central heating. Yet in contrast, in some respects they were not brilliant. A missed opportunity, surely, was their failure to accept the healing methods taught by Jesus. For an Empire obsessed with military power, a more effective method of healing their Army's casualties sadly was overlooked.

Although the Empire lasted until the year 1 453 when Constantinople was captured by the Turks, Edward Gibbon tells us of another serious mistake. In his eight volume masterpiece Decline and Fall of the Roman Empire we are told that Emperor Justinian in the sixth century asked some monks to go to China to get some silk worms. This project was successful and they were brought back to Constantinople to start silk production. However, China experienced some nasty rebellions in the 7th and 8th centuries, which obviously delayed any needed development work with printing. The development of printing was more successful in the 9th century. Without doubt, the people of the Roman Empire could have been greatly enriched if the skills of printing had been brought back to them. Then again, with all their sophistication in managing civil affairs, one can add sadly, they never discovered the value of Adult Education!

This reminds me of the tremendous interest during the late 70's after the thrilling discovery of the passage of the Indian subcontinent. Teaching geology in my Adult Education class, we were absorbed with the deep study of how that ocean had evolved. One of the details included in this study was the small basaltic island of Kerguelen in the southern part of the Indian Ocean. However, knowledge was limited in those days. Apart from knowing it was composed of basalt, and that it is part of the submerged KerguelenGaussberg Ridge, little else was known. In broad terms it was somehow connected with the break-up of Gondwana which began about 130Ma ago.

Deep-sea drilling equipment is certainly not new, but having used it to study the main features of the Earth's oceans, the technique can now investigate the lesser-known parts. For example, the sunken Kerguelen plateau has recently come in for considerable close study. Instead of being known simply as basaltic, deep-sea drilling has revealed it to be partly composed of metamorphic rocks. Now, we know these rocks are formed at great depth and under high pressure and temperature.

Any one who has read my earlier articles in this Journal will know about garnet crystals and how they are formed. This discovery of metamorphic rock from deep below Kerguelen they now know is garnet-bearing! This means that it needed to be buried for some time deep in the crust; and also that it was associated with mountain-building. Then, as proof that this rock had at one time been above sea level, the scientists on board the drilling ship discovered examples of plant spores, seeds, pollen, as well as some charcoal and wood fragments in the sediments.

We have proof that this submerged landmass, which is now 2 000 metres below the surface, was connected to Broken Ridge to the north-west. The remains of fossilized marine plankton show that Kerguelen rose above sea-level three times. That is certainly unique. The dates are: 110Ma, 85Ma and 35Ma. The crust would have been pushed up by the very intense volcanic activity of a magma plume. Then as the plume cooled, the crust gradually slipped down below the waves.

It is clear why this cycle of events repeated itself in the same place; it was because this part of the ocean floor was moving very slowly over this "hot spot". The mid-ocean ridge towards the north of Kerguelen produced new ocean floor which was moving southwards and this counteracted the general northward movement towards Asia.

It is also estimated that the land surface at the time of maximum uplift could have been as great as 2 million square kilometres. Probably, this landmass played a part in the migration of animals after the break-up of the supercontinent of Gondwana.

Compared with Roman times, we are grateful for modern research technologies, for the versatile use of printing, and for Adult Education. The Roman people certainly missed out on many things! ·