Collaboration between George P.L. Walker and Icelandic and foreign geoscientists, 1956-76

1. Notes on collaboration between George P.L. Walker and some Icelandic and foreign geoscientists, c. 1956-76 Leó Kristjánsson Institute of Earth Sciences, University of Iceland

2. This short account is no doubt one of hundreds that the many students, co-workers and successors of George Walker worldwide could tell about their experiences of him, his research and subsequent progress in volcanic geology. Most of these people, including some present here today, had much more contacts with him than myself. It is therefore a great honour to be asked to to reminisce about a small part of Walker’s pioneering contributions to the geology of Iceland. This example largely concerns his collaboration with Thorbjörn Sigurgeirsson which in fact had a decisive effect on my own career from 1964 on. A “native bearer” washing his socks at a tent camp in East Iceland, 1964

3. When George Walker’s research in Iceland began in 1955, the general geology of the island had not been investigated much since the travels of Thorvaldur Thoroddsen in 1882-98. Icelandic and foreign scientists from the beginning primarily directed their attention to specific occurrences and sites: volcanic eruptions, historical lava flows, geothermal manifestations, lignites, fossils, palagonite and its alteration, zeolites and other minerals, sea-level changes, avalanches, earthquakes, glacial remains, and a few mountains such as Baula. The older formations outside the volcanic areas were (until 1968) thought to be of Eocene age, i.e. 50 - 60 M.y. old, and a very dull subject. W E G. Bárðarson’s cross-section of Iceland, from his textbook used in Icelandic schools 1927-68

4. Around 1955, only three Icelandic geologists were engaged mostly in research: • - Sigurður Þórarinsson (volcanism, tephra layers, glaciers, etc.) • Guðmundur Kjartansson (geological mapping, glacial geology, • construction projects) • - Tómas Tryggvason (economic geology) • and a few were studying abroad, including Jón Jónsson og • Þorleifur Einarsson. • As far as I know, George Walker did not collaborate actively with these or other Icelandic geologists, except his graduate students later on. Haraldur Sigurdsson thanks him for advice and help in his B.Sc. thesis work in Snæfellsnes 1963-64. • Walker came to be greatly respected by Icelandic scientists, and was elected corresponding member of the Societas Scientiarum Islandica in1968 (years before becoming an F.R.S.)

5. Around 1955, three Icelanders educated in different fields, were active in geoscience research in the country: Trausti EinarssonÞorbjörn SigurgeirssonGunnar Böðvarsson astronomer, physicist, manager of mechanical engineer at the professor National Res. Council State Drilling Contractors They soon saw the great new potential for research based on the mapping by George Walker and his students of Iceland’s geological formations.

6. Let us start with Gunnar Böðvarsson who published in 1964 a joint paper with George Walker. They pointed out that some aspects of Icelandic geology indicated gradual extension of the crust by dyke intrusions. Due to many compli- cations and unknown factors, they however left other interpretation possibilities open. B & W The Böðvarsson and Walker paper, completed in 1963, was quite independent of the famous one by F. Vine and D. Matthews on crustal rifting at ocean ridges which appeared in September of that year. Magnetic anomalies V & M

7. Things happened fast in the general acceptance of crustal spreading in 1963-64, and the Surtsey eruption also emphasised the role of fissures in the crust. George Walker was by early 1964 convinced of the reality of rifting, and his writings helped to convert most Icelandic geoscientists in the next 2-3 years. Gunnar Böðvarsson emigrated to the U.S. in 1964 and his scientific collabor- ation with Walker did not continue. Guðmundur Pálmason who became Gunnar’s successor as head of the Geothermal Division of the State Electricity Authority, continued investigating similar matters after 1970, in his numerical models of accretion, heat flow etc.

8. Trausti Einarsson wrote a very positive review of Walker’s first papers on Iceland, in the natural history journal “Náttúrufræðingurinn” 1960..... ...and they corresponded for many years, although their ideas on the geological structure of Iceland later became quite divergent: 1963

9. We now have to scroll back to1950-51 when a Cambridge University student came to Iceland to sample rocks for the measurement of their magnetic remanence directions. Trausti and Thorbjörn met him and saw the potential of such measurements. They began systematic surveying of these directions in lava sequences in 1953, employing very simple equipment. They travelled all over Iceland for this purpose during the next few years, and Thorbjörn also constructed an accurate laboratory magnetometer for samples. Their results showed that the geomagnetic field had reversed at irregular intervals so that the lava pile could be divided into zones having magnetic directions like at the present (N) or opposite (R).

10. It so happened that P.M.S. Blackett who received the Nobel prize in Physics in 1948 for cosmic-ray work, had become interested in magnetic fields around stars and planets. By 1951, he was also doing research on the magnetization of rocks. His Manchester facilities for rock-magnetic studies were moved to Imperial College when he became Professor there in 1953. The results of Trausti and Thorbjörn generated wide interest and disposed of incorrect notions about the nature of rock magnetism as well as about the history of the geomagnetic field. They presented landmark papers at an important conference on rock magnetism in London in 1956, chaired by Blackett. From a paper by T.E. in 1957

11. Thorbjörn may have established contact with George Walker by 1956... ..... and provided some support for him from Icelandic funds in 1961-63:

12. Trausti and Thorbjörn were given copies of Walker’s detailed draft maps: In Thorbjörn’s copy above, “reverse” polarity of mag- netic directions in lavas is red and “normal” is blue. These were in some cases also shown on photos.

13. They saw here a possibility of a new method to augment Walker’s mapping efforts, at the same time yielding results of global value for scientists. At Walker’s initiative (probably in 1961-62) a project of sampling hundreds of lava flows in a composite section through the whole East Iceland lava pile was envisaged. In a visit by Thorbjörn to Imperial College in late 1963 it was agreed to apply for funds and start preparations for an expedition. The leader of the expedition was R.L. Wilson, Blackett’s former Ph.D. student with experience from Northern Ireland lava flows.

14. The expedition began in June 1964 with the collection of samples from 300 lavas in SW-Iceland, mapped by Trausti Einarsson. New petrol-powered diamond core drills brought from the U.S. by one participant, N.D. Watkins, proved superior to the previous method of taking hand samples.

15. This was followed up by the collection of core samples from some 1100 lava flows in East Iceland in 1964-65. 1964 1965 1964-65 It was at that time by far the largest project of its kind on igneous rocks.

16. Walker provided first-class drawings of each profile just in time, and painted yellow numbers on the lava outcrops. The profile on the left is in mt. Skagafell near the Egilsstaðir- Reyðarfjörður road. It was composed of 59 lavas, all of “normal” magnetic polarity.

17. Here is another drawing which shows the top part of a 39-lava profile just east of Neskaupstaður. A German expedition collected more samples nearby in 2005 and added another segment (Nes1) below.

18. George Walker on the left with local kids and expedition members, SE-Iceland 1964

19. Professor Blackett paid a visit to the expedition camp while the oldest lava flows in East Iceland were being sampled, and was quite impressed:

20. c. 2 M.y. ago After subtraction of profile overlaps, the East Iceland composite lava section amounted to 8½ km in thickness. A 1967 paper in Nature describing results on lava polarities was accompanied by an editorial: The geomagnetic polarity had clearly reversed at least 60 times in a time interval of about 11 million years, according to radiometric dates published in 1968. This was a higher frequency than previously anticipated. The 1964-65 expeditions resulted in more than 40 papers and several theses. They aided the further progress of crustal-rifting and plate tectonics concepts which were in part based on magnetic anomaly interpretation. c. 13 M.y. ago

21. The above-mentioned participant N.D. Watkins later returned to Iceland to initiate several new projects in stratigraphy and magnetic measurements on long composite sections. These (totalling > 2400 lava flows 1972-78) were carried out in collaboration with Icelandic scientists and an expert in radiometric dating, I. McDougall. A large paper on the 1964-65 field project was also completed, and some additional work was done in the East Iceland profiles. 72 pp. This essentially concludes my account of some of George Walker’s collaborative projects, but he wrote additional important papers on the geology of Iceland in the 1970’s, for instance two in the conference volume “Geodynamics of Iceland and the North Atlantic Area” 1974. One of these was inspired by a visit to the Heimaey eruption in 1973.

22. Final comments The number of active Icelandic geologists is no longer three as in 1955: some 300 have (since 1972) received B.Sc. degrees in geology from the University of Iceland, and there are many geoscientists with foreign degrees or education in related fields. In the very useful work which they are doing for the country and for science, they have no doubt been inspired by the pioneering studies of George Walker on volcanic formations and processes both here and internationally. In the older parts of Iceland however, I feel that we Icelanders have not carried on geological research with a momentum as could have been anticipated back around 1970, say. This applies to the general stratigraphy and structure of the Tertiary lava pile that is so evident here in Breiðdalsvík, as well as to many specific features such as its primary petrology, its central volcanoes, interbasaltic sediments, tectonics, hydrothermal alteration, and so on. I hope that the centre which has now been opened, will contribute to a revival of interest in these matters among both Icelandic and foreign geoscientists. I also hope that the centre will help in informing students, travellers and the general public about the many geological wonders of East Iceland.

23. Thank you for your attention Walker’s LandRover on the left, SE-Iceland 1964