Yngve Kristoffersen

Walter Pitman – tribute to a mentor from a foreign student

Walter at the computer in Claremont Avenue in December 2011

I first met Walter Pitman III, his wife Ginger and daughter Cordelia outside the Munch Art Museum in Oslo in May 1971. With a fresh MSc. in geophysics, I had been awarded a Norwegian fellowship to go to Lamont for one year. It ended up with 5.5 years and a PhD before returning home. The story is a classic example of scientific networking and international scientific cooperation.

The Norwegian effort within the IUGG Upper Mantle Project (1964-70) and the following Geodynamics Project (1972-79) focused on a 100 km wide geotraverse across the southern part of the country. Professor Knut Heier, University of Oslo was our national project chair. Maurice Ewing called Heier in the fall of 1969 and asked if he could come to Oslo «for a few days to speak to some of you». The result was an extension of the Geotraverse across the Norwegian Sea to the island of Jan Mayen. By that time, the Vema had already carried out 2 cruises in 1966 and 3 cruises in 1969 in the Norwegian-Greenland Sea. Manik Talwani had been Chief Scientist on 3 of these. Before Manik arrived at Columbia University in 1953, he had spent 7 months at the Geophysical Prospecting Laboratory of the Norwegian Geological Survey in Trondheim on a Norwegian scholarship. This experience probably contributed to his later interest in the Norwegian Sea as part of the larger North Atlantic Ocean. Between 1966 and the end of 1973, the Vema carried out a total of 12 cruises in the Norwegian-Greenland Sea. I got the opportunity to participate in V2802 in 1970 with Charlie Windish as Chief Scientist and our family of three arrived at Lamont in August 1971. The Geotraverse cooperation gave four young Norwegian scientists the opportunity to spend a year at Lamont. Three of them later pursued a career in science at Norwegian universities. One left Lamont directly for industry and became exploration manager with Shell.

My background was magnetics and gravity applied to a plutonic intrusion in the Oslo Rift. At Lamont, I admit discussions at the lunch table threw me off a bit during my first half year. I needed time to catch up with the range of topics and detailed knowledge of geologic features in remote parts of the world’s oceans. My desk was in the Magnetics Department in the Oceanography building where Walter moved quietly around and always had time to talk. Steve Cande and John LaBrecque were contemporaries. I enjoyed the challenge of catching up in understanding how the Earth works, and quickly realized it would be a grave mistake to return home without a formal degree. However, the Norwegian funding was only for one year, but through a friend, we got a situation where I could work 60 hours a month for the rent and my wife Maj Britt took care of the landlord’s kids. We now had money for food also. The arrangement was illegal, but the intensions were the best.

Manik took me on as graduate student and the challenge was the triple-junction in the Labrador Sea south of Greenland. It was mostly an exercise in marine magnetics with tectonic implications around the entire circumference of Greenland. One of the fascinating aspects of the plate tectonic concept is the capability to predict geologic consequences for other remote parts of the plate boundary. The LDEO directorship kept Manik very busy and at one point he did not get to time discuss our science progress for 6 months. However, I could always try out ideas on Walter. He let you know what he thought, but did not push it. The Pitman and Talwani paper on the opening of the North Atlantic had just come out and Walter was now intrigued by what had happened in the Arctic Ocean. The student symbiosis with an enthusiastic Steve Cande and the roaming mind of John LaBrecque was invaluable. The Magnetics module on the 2nd floor in Oceanography with the adjacent offices of Walter and Roger Larson often became a gathering place and ideas flowed. Once a well-dressed older gentleman suddenly arrived. He had been directed to see Walter. «I have a theory about the Earth», he said and laid it out in front of the blackboard. Walter’s body language was unmistakable, but kindly told the gentleman his proposition was unrealistic. Without a sign of disappointment, the person went on; «I have another theory». Unfortunately, the fate of both ideas was the same. No offence, the man lifted his hat and said «Good bye». Walter chuckled.

A drawing by Portia Takajan symbolizing the research at the Magnetics Department.

For a graduate student to be entrusted with a fully equipped research vessel for two cruises into your thesis area, was a tremendous learning experience I fully enjoyed. Manik had 15 minutes with me before the first cruise to discuss a detailed survey strategy. He drew a box around the triple-junction and said, «Don’t get out of the box before you think you have it nailed». The realization that you were in fact navigating by the age of the sea floor to map out the triple-junction, was mind boggling. On return to Reykjavik during V3009, Marcus Langseth directed me to take a series of heat flow measurements across the Reykjanes Ridge. The low values over the rift valley surprised me, but Marcus smiled; «it demonstrates convective heat loss». Doc’s philosophy of simultaneous gathering multiple data sets, was something I liked and have since tried to pursue in my career.

Two memorable incidents at Lamont pertain to the inspiring evolution of scientific progress. The concept of a global sea level curve as a tool for stratigraphic dating in frontier areas had been developed by the Exxon research group and quickly attracted wide scientific interest. Peter Vail gave a Friday talk at Lamont Hall and explained how the Exxon seismic data base could document coherent global sea level fluctuations through geologic time. «Where did the water come from and where did it go»? the audience asked. «I don’t know», was Peter’s honest answer which immediately contracted a loud «hmmm» from the crowd. This was food for thought, and the rest is history addressed in subsequent papers by Watts, Ryan and Pitman. The other incident was a sudden uncontrolled extended roar from Roger Larson’s office, a sound from an otherwise «soft spoken» Iowan that penetrated concrete walls. In his search for Cretaceous magnetic lineations, Roger had just received copy of a thesis about the Argo abyssal plain northwest of Australia. The area had now been drilled and the predicted age using the Heirtzler et al. time scale was >40 million years too young. Roger turned the page with the stacked magnetic profiles upside-down and there was the M-series! The young Larson went ballistic for a moment and high on adrenalin he wrote a paper the same afternoon.

A summary of my thesis was published in the GSA Bulletin and I also worked with Steve Cande on reinterpreting Late Cretaceous magnetic anomalies in the eastern North Atlantic. I have always had a strong interest in looking at rocks in the field to get a visualization of the realities behind geophysical models. My scientific interest and friendship with a fellow student, Robert Jacobi brought me to Newfoundland to visit all the classical ophiolite locations. We also wrote a paper on correlation of geologic structures across the North Atlantic mostly based on potential field data.

Towards the end of our stay at Lamont, my wife and I had factored completion of my thesis into our family planning. Unfortunately, the first part was harder than the last and our healthy son arrived six months before the cost would have been picked up by the free for all Norwegian medicare system.

We returned to Norway in January 1977 and I got an appointment with the Norwegian Polar Institute in Oslo. From 1984, I have held a professorship in geophysics at the Department of Earth Science, University of Bergen. Walter used to call us every Christmas Eve, a tradition he continued for about thirty years. During all my visits to New York over the years, I was invited to stay at the «Pitman Hotel» in Claremont Avenue. Our entire family (4) stayed there to attend the 50-year LDEO anniversary in 1999. The Lamont-years had been an important part of our lives. My 8-month sabbatical in 1998 was also spent at Lamont. I invited Walter to come to Norway to give talks on the sea level issue in 1989 and also in 1995 on early ideas on «The Flood». We went north to see my home town Alta at 70° N in 1995. Alta has a fantastic example of the Younger Dryas end moraine (75 m high, 600 m. wide) which cuts across the 10 km wide valley and is breached on the eastern side by a well-known salmon river. The end moraine was formed in a   ̴500 year long cold spell which ended about 11.500 years ago during the deglaciation of the Fennoscandian ice sheet. The Younger Dryas moraines  encircle the entire coast of Norway, cuts across southern Sweden and continue across southern Finland. Another attraction in Alta is a large World Heritage field of 2-4000 year old rock carvings.

There are at least three major benefits of studying abroad: i) you get a degree from a reputable institution, ii) you get exposed and challenged by other ways of thinking, and iii) you get an international network of fellow scientists. An example of the latter is my discussions with a young student named Paul Wessel as he was winding up his thesis on gravity inversion of the Oslo Rift at the University of Oslo in 1984. I called up Tony Watts at Lamont and presented the case. «I’ll see what I can do», said Tony and many of you know of Wessel’s subsequent professional merits at Lamont and later at Hawaii.

My scientific interest in the polar areas had always been there, but the logistic issues were overwhelming. The Office of Naval Research sponsored a series of field experiments from drifting sea ice (1979-1982) with the LDEO and MIT/WHOI groups as the main operators. Norway was invited to participate and I connected up with Ken Hunkins’ group and organized several projects for the 1979 and 1982 field seasons.

Norway became a member of ODP in 1986 through a European Consortiumn and the educational experience of being Co-Chief Scientist on Leg 114 in the South Atlantic, was profound. Scientific drilling in the Arctic Ocean soon became a dream for many of us. In 1991 we got the opportunity to document the capacity of a single icebreaker to maintain site in 1-2 m of drifting sea and this opened up new perspectives. As a member of ODP-TEDCOM at the time, I started to consider the case of drilling in an ice-covered ocean with no need for heave compensation. Trials using our 150-foot university research vessel and a land prospecting drill rig were promising. Our first endeavor was from the Finnish research vessel Aranda and yielded 16-meter penetration in diamicton on the Weddel Sea shelf, Antarctica in 1996. A US effort of shallow drilling from a research vessel in Antarctica, have since followed. Our next challenge in 1996 was shallow drilling on Lomonosov Ridge in the central Arctic Ocean. Our Swedish colleagues were excited and had cut a 1 m. diameter moon pool through the hull of the icebreaker ODEN. We set the riser in 962 m. water depth on top of the ridge about 200 km from the North Pole. Unfortunately, the drill string got stuck in the riser at 250 m on the way down. The plastic riser had been pinched by ice during deployment and the attempt had to be aborted. Nevertheless, the effort served as a powerful preamble for increased science community pressure which resulted in the successful IODP 3-ship Arctic Coring Expedition in 2004.

Walter and Bill Ryan’s work on the flood hypothesis fascinated me and was often the talking point during my visits to the «the Pitman Hotel». Our roaming discussions more than once ended up with Walter’s vivid description of what went on when his old mother had decided to buy a new car. An added subject was my idea of a possible impact of asteroid fragments in 1500-200 m. water depth in the central Arctic Ocean. The few multi-channel seismic lines available showed no evidence of major bottom-current regimes in the Arctic Ocean. However, the LDEO Geophysical Data Summary for Fletchers Ice Island (T-3) and John K. Hall’s 1979 paper on sediment waves on Alpha Ridge told an entirely different story. The seabed was disturbed and massive submarine slides occurred within a 200 x 600 km area on top of Alpha Ridge. There appeared to be no crater, but in some places >100 m of stratigraphy had been blown away and T-3 had recovered Late Cretaceous-Eocene sediments in slide deposits. The simplest explanation was the disturbance from a pressure wave generated by impacting asteroid fragments and the   ̴30 m. thick drape over the disturbance suggests a Pliocene age. The elongated area happens to be on the great circle which includes the Eltanin impact (2.75 Ma.) in the SE Pacific. «This is an interesting paper, but I don’t like it», remarked one reviewer and it took three attempts to get it published. Nevertheless, the idea has so far stood the test of all new seismic and multibeam data.

The asteroid idea was exciting, but the opportunity to access stratigraphy representing the Arctic «Greenhouse» environment would be paramount to anything else. I invited John K. Hall (Columbia graduate of 1970) to Bergen in 2004 for a week to discuss. As a graduate student for Ken Hunkins, he had collected some of the T-3 seismic data. We needed to get to Alpha Ridge and get cores. I had developed and patented a sediment corer which shot the core barrel into the seabed like a projectile driven by the water pressure. I also told John about my past efforts to test out hovercraft in the Arctic. He looked at me, «Let us buy one», he said. The first polar hovercraft research platform has low operating costs, can carry a payload of 2 tons and the capacity to do seismic reflection, take sediment cores, do dredging and take CTD measurements. It can access areas out of reach for icebreaker surveys and has spent 18 months drifting with the sea ice and travelled over 4.000 km between Svalbard and the North Pole. The fuel consumption for 1 year of ice drift with the hovercraft equals what an icebreaker burns every 6 hours. Our next challenge is to document the feasibility of doing swath bathymetry and seismic surveys from drifting sea ice.

My wife Maj Britt in a discussion with Walter

During visits to «the Pitman Hotel», I always found opportunities to enter the Columbia Campus, sit on the stairs to the Low Library, look at students passing by and let the thoughts flow. It has become a ritual in all my visits to New York. Each individual moving past has ambitions and hopes for a prosperous future, but are heading into a society which needs to change its perception of life on the Earth; perpetual growth is not sustainable. Walter’s personality made him a natural mentor. The essence of a great mentor is not in imparting important facts on the student, but freeing his/her imagination to discover for themselves what is important. I am grateful for the privilege of having known Walter Pitman III.

Yngve Kristoffersen (graduate of 1977)

Department of Earth Science, University of Bergen

Norway