Earth Sciences in Bristol trace their roots back to 1876 to University College, Bristol - which would become the University in 1909. But Bristol Earth Sciences' pioneering research goes back far further, to the Precambrian period more than 600 million years ago, investigating ancient fossils and uncovering why dinosaur feathers were different colours, and far deeper, hundreds of kilometres within the earth, to understand how the properties of trace elements can be used to decipher processes such as volcanism. Bristol's researchers looked to space, winning a NASA gold medal for studying moon rocks, and examined the inner workings of volcanoes and the miniature clues to the deep Earth contained within diamonds.
The excellent reputation of the Earth Sciences department for palaeontology dates back to 1867, when geology was first taught. One of the first professors was W. J. Sollas, the great Victorian expert in teasing out the subtle anatomy of ancient fossilized organisms. He pioneered a technique called serial sectioning, where complex fossils - whether shells or ichthyosaur skulls - were sliced or ground away millimetre by millimetre. The anatomy of each slice was traced, and then the many slices could be reassembled in a glass model that highlighted all the internal features. This was the foundation for today's remote scanning techniques, used, for example, at the European synchrotron in Zurich, which allow Bristol's palaeontologists to peer inside tiny fossil embryos only millimetres across. This research has played a critical part in the ground-breaking studies of evolution in some of the earliest animals.
Derek Briggs, professor from 1985-2005, was a leader in a method known as taphonomy: the performing of experiments on rotting carcasses in temperature- and pH-controlled surroundings. Taphonomy enables scientists to understand how some fossils are astonishingly well preserved, showing even soft tissues such as skin and muscles. Briggs showed, for example, that phosphate minerals can be laid down within days by bacterial action which “freezes” labile tissues such as muscles and eyeballs before they rot. Continuing this work, Mike Benton, current head of the department's Palaeontology and Biodiversity Group, recently discovered the structures within dinosaur feathers that were responsible for their black, grey and reddish colours.
The early 1990's were heady times in the fields of geochemistry, mineralogy and petrology, as Bristol developed high pressure and temperature experimental facilities capable of reproducing conditions equivalent to depths within the Earth of 600 km or so. Bristol’s international reputation for deep earth research began with the arrival of Bernard Wood from Northwestern University in the US. Using existing workshop facilities and personnel to build a succession of experimental apparatus, Wood turned Bristol into the UK’s leading experimental facility. Together with colleague Jon Blundy, Wood set about testing one of the building blocks of trace element geochemistry as first proposed in the 1930’s by Victor Moritz Goldschmidt, the Swiss-born “grandfather” of modern geochemistry.
Goldschmidt had recognised the potential of using trace elements, present in natural rocks and minerals at concentrations of parts per million or less, to unravel differentiation processes in the Earth such as separation of the core and atmosphere, volcanism and crustal growth. He realised that this required an understanding of how trace elements behave in complex systems, such as magmas, and argued that it was the size and charge of trace element ions that were the dominant factors. These so-called “Goldschmidt’s Rules” guided much geochemical progress over the ensuing decades with the growth of geochemists’ ability to analyse vanishingly small quantities of different trace elements in rocks using ever more sophisticated mass spectrometry.
Blundy and Wood devised a set of high temperature and pressure experiments to test Goldschmidt’s Rules, analysing the quenched run products using novel ion-microbeam techniques. They discovered that, although impressively prescient, Goldschmidt was not quite right; Blundy and Wood confirmed the twin importance of ionic size and charge, but with the added complication of the elastic response of the crystal lattice into which the trace ions were located. Their Lattice Strain Model of trace element partitioning, which innovatively linked macroscopic crystal properties to the behaviour of trace impurities, has now achieved universal acceptance and spawned many follow up studies. Both continued to explore the opportunities to reproduce deep earth processes such as the formation of the core (Wood) and the subterranean workings of volcanic magma chambers (Blundy) in the laboratory.
Modern organic geochemistry owes a great deal to Bristol researchers, who developed a number of the standard techniques young researchers now take for granted. The pioneer was Professor Geoff Eglinton, who studied under chemistry Nobel Laureate Melvin Calvin, and shared appointments in both the Chemistry and Earth Sciences schools. Eglinton invented geochemical methods for using biomarkers to assess the maturity and biological source of petroleum, setting the stage for the field of biostratigraphy and having vital implications for studying the origins of life. The Eglinton Reaction is now a standard technique for coupling terminal alkynes (a class of hydrocarbons).
In 1971, Eglinton - who has won many awards including the Royal Society’s Royal Medal, the Goldschmidt Award, and most recently the Dan David Prize - led the well-known study of moon rocks that showed that there was no indication of life in the samples, garnering him a NASA gold medal for exceptional scientific achievement. For nearly three decades Eglinton’s research group in Bristol produced ground-breaking research in a diverse range of areas and trained generations of young organic geochemists, making profound contributions such as the development of molecular yardsticks for palaeoclimate studies – and even explaining the significance of rabbit droppings in the sedimentary record.
In 1989, volcanologist Steve Sparks left Cambridge and, with Wood, built The School of Earth Sciences into on of the top departments in the UK. Sparks is the most cited volcanologist in the world, according to ISI Thompson. His early work on pyroclastic flows and the importance of magma mixing led to some of the first fluid dynamical models of explosive eruptions and degassing, which in turn inspired pioneering research on the physics of volcanic plumes and the dispersal of volcanic ejecta.
In the mid 1990's, Bristol spearheaded research on the eruption of the Soufriere Hills volcano, Montserrat, now regarded as the world’s best-documented andesite island arc volcano. The state-of-the-art geophysical fluid dynamics laboratory has seen cutting-edge laboratory experiments such as those on explosive multiphase phase flows in shock tubes done with Heidy Mader and Jeremy Phillips. Field and laboratory studies provided the underpinning for numerical research into volcanological processes, including the early development of models of non-linear dynamics of magma flows in both explosive and lava dome eruptions.
More recently, exploring the broader problem of crustal magmatism, Sparks, working with Blundy and Catherine Annen, developed the Deep Crustal Hot-Zone Model which has already been accepted as a new paradigm. Working with the De Beers diamond company, Sparks and his colleagues have formulated a new view of kimberlites, the host rocks for diamonds, which challenges the interpretation of both kimberlite geology and petrology with its recognition of a new fluidised regime in volcanic conduit flows.