Citation for the 2001 award of the W.A. Johnston Medal
It is a great pleasure for me to write this citation for my friend and colleague Derek Ford on the occasion of his receiving the Johnston Medal. Derek is truly deserving of this recognition for his research on the Quaternary era. His studies of caves and speleothems as recorders of climate and geomorphic evolution have been recognized throughout the world, as exemplified by the numerous awards and recognitions he has already received, including the Gold Medal of the Royal Canadian Geographical Society for his studies of Castleguard Cave, the G.K. Gilbert Award of the American Association of Geographers, and fellowship in the Royal Society of Canada.
Derek began his career at Oxford University where he did a degree under the supervision of the noted speleologist Margaret Sweeting. He studied the Mendip Caves near his home in Bath, and in subsequent years often returned to these caves to gain further insights in speleogenesis and in order to sample the stalagmites that these caves contained. In 1959 he came to McMaster, leaving briefly to try out the climate of southern California, but soon returning the Mac where he remained until his retirement in 1997. His research, however, has taken him to every corner of the world where caves can be found, from Brazil to northern Norway, from China to the Cayman Islands, from New Zealand to the Northwest Territories. There can hardly be a significant karstic terrain in the world that Derek has not investigated.
His travels have allowed him to study caves in four dimensions, observing their present-day form, and using both his geographical insights, and a variety of dating methods to infer the ways in which these underground features have evolved through time by the slow dissolution of carbonate and evaporite bedrocks. These insights were synthesized from a multitude of careful studies by himself and his many graduate students and post-docs. They allowed him to develop a comprehensive theory for the origin of cave systems, a theory which became the dominant view for the majority of students of cave development and has been borne out by studies of other researchers around the world.
At the same time, starting in the 1970’s, Derek collaborated with various students as well as myself to develop a program of paleoclimate studies based on the dating and isotopic analysis of speleothems. Thanks to his broad awareness of the areas in which samples would be available for study, this program of research laid the foundations for a new insight into the history of continental climate over the past hundreds of millennia. He appreciated that this record had to be correlated with other existing records such as the isotopic signals from deep-sea sediments and ice cores from the Arctic and Antarctic. After some years of neglect, we are now seeing a world-wide revival of interest in isotopic studies of speleothems, so that this once arcane subject is now appreciated as an important input into our tracking of past glacial-interglacial transitions.
Intimately connected with these studies, Derek also maintained a close interest in the role of karst as a carrier of water. He became widely sought as a consultant on karstic hydrological systems, which provide the world with some of its most complex and inscrutable hosts for groundwater. In recognition of this work, he was awarded the 1999 first Annual Award of the Karst Waters Institute of America.
In the 1990’s, he happened to encounter another cave enthusiast, Yavor Shopov from Sofia, Bulgaria, who had a wonderful way of using laser beams to discern seasonal cycles in speleothems. Bringing Yavor to McMaster was a wild and woolly adventure, and allowed Yavor to broadcast his ideas more freely to the speleothem community.
These are just some highlights of the diverse and fruitful universe of ideas that Derek has harvested through his career. The Johnston Medal justly honours the life-long work of an underground genius, a man who has led a small army of bright young men and women into the stygian depths where they could achieve enlightenment. Virtually all of the academic speleologists in the English-speaking world, and many of those from the rest of the karstic field have either been students of Derek’s or have spent time in his labs. His book with Paul Williams has become a bible for those interested in the study karstic caves and hydrology.
The Quaternary Research community of Canada is fortunate to claim Derek as a member in good standing. He has been recognized both at home and around the world for his singular achievements in the study of the holes that lie beneath our feet as we stand on any limestone bedrock. The Johnston Medal is an appropriate further honour for these achievements. I look forward to his continued stimulus to myself and his many other research associates and students. Although he has moved off to Orillia, a few hours away from Hamilton, we await his regular visits to check up on how things are going with his technicians, students and the steady stream of visiting scientists who are attracted to the lab.
Henry Schwarcz, McMaster University
It is a great honour to be a winner of CANQUA’s Johnston Award for 2001 in the company of Wes Blake, a good friend and colleague for many years.
I started to study Quaternary phenomena with a 1956 undergraduate expedition to map the recession of the most northerly icecap in arctic Norway. Quaternary science has made enormous advances worldwide since then and is certainly one of the most complex and worthwhile of interdisciplinary fields today. There is a lot more exciting discovery to come. For those younger CANQUA members who will be contributing to it I would like to offer some perspective from my own experience in the field.
As Henry Schwarz notes, much of my career has been dedicated to dating of and paleo-environmental work on speleothems, stalactites, stalagmites and flowstones of calcite or aragonite that are precipitated in limestone caves. As a cave specialist I appreciated that these slowly accumulating deposits that can be seen growing on top of or buried within more conventional fluvial, lacustrine, aeolian or even glacial, sediments in ancient caves might contribute a lot to Quaternary chronology if they could be dated by some means. In 1962 a leading American specialist, John Rosholt, suggested that they would not be suitable materials for U series isotope ratio dating because they lacked sufficient uranium and suffered from detrital thorium contamination problems. In 1965, however, the “father of U series dating”, V.V.Cherdyntsev, published some apparently successful results from speleothems and spring travertines in Russia. Henry Schwarcz, an isotope geochemist newly arrived at McMaster University, and I immediately decided to undertake an investigation to resolve the question. Our history of speleothem dating since then is an interesting and optimistic example of progress in scientific technology.
We began by using alpha particle radio emissions to measure the isotope ratios, the standard method of the 1960s and Œ70s. Anywhere from 40 to 100 grams of calcite would be required for one dating attempt, creating a big and ugly hole in the stalagmite – i.e., the temporal resolution within a given sample was pretty poor. After extraction, the U and Th in our samples sat for one week or more in alpha counters to accumulate a few thousand disintegrations. With such numbers the one standard deviation error of the age estimate was then about +/-10%. When we last bought an alpha counting system, in 1980, it cost $25,000.
In the 1980s our McMaster colleague, Alan Dickin, took some of our dated speleothem samples to experiment with thermal ionisation mass spectrometry, his specialty. We were beaten to the draw by Edwards, Chen and Wasserburg (Caltech) who published successful results on calcite corals in 1996/7. Our first clear successes with speleothems came one year later. “TIMS” is now the standard method for U dating calcites. The size of individual samples is usually no more than one gram and can be much less if a deposit is old. The dating range is pushed back from ~350,000 years BP to 500,000 – 600,000 years in favorable circumstances and the one standard deviation error is reduced to about 1% or less. U can be counted in automatic mode overnight while you are out at the pub but, with current technology, a skilled person is needed to control the thorium counting, paying close attention to the monitor for about three hours per sample. A suitable mass spectrometer costs $250,000 or more.
During the past two years U series dating of speleothems has been tried on induction-coupled plasma mass spectrometers (“ICPMS”). It works! Both the uranium and thorium isotopes of a given sample can be counted in just 20 minutes. Running on the ICPMS machine at GEOTOP, Montreal, our McMaster speleothem standard yields an age of 15,750 years BP with a two standard deviation error of 30 years – which is probably less than the actual span of time that it took the calcite of the sample to accumulate in the first place. Suitable machines cost more than $1,000,000 but just think – inflation!
In other speleothem work we are now resolving calcite deposition to individual years or even to seasons within them. I am sure that there are similar successes to come everywhere else in Quaternary studies. Most impressive are recent results by Darryl Granger and Derek Fabel (Purdue University) studying the radioactive decay of cosmogenic 26Al and 10Be in the skins of quartz sands washed into Mammoth Cave, Kentucky, and so removed from further cosmic bombardment. Quartz grains one metre or more below the surface in any glacial deposits should be similarly protected. The one standard deviation error of 26Al, 10Be dating is now about the same as it was in our U series technology c.1975.