Professor Dan McKenzie, 60, a fellow of King's College, Cambridge, is renowned for his work on earth sciences, the study of the planet's mechanics and physical properties.
A winner of the Wollaston Medal of the Geological Society of London - the most prestigious award in geology - Professor McKenzie played a pivotal role in working out how tectonic plates on the earth's crust move across a roughly spherical surface. He extended his theory, conceived to explain oceanic faults, to the tectonics of continents, and has carried out research on the earth's mantle, the moving layer between crust and core.
"As an undergraduate, I had to start a new subject and the choice was physiology or geo- logy. I took all the books out of the library on both subjects and found those on physiology to be dull medical texts, of the most plodding kind. The library's only geological books were Lyell's Principles of Geology and Geikie's book on the ancient volcanoes of Great Britain. And I thought they were wonderful and decided to read geology.
"My career highlight has been the discovery of plate tectonics - of how sedimentary basins are formed by extension, and of how the mantle melts to make basalt.
"Successful geologists need curiosity, a liking for field trips and an ability to do sums. Almost everyone I know with experience of geological research has fallen in love with the subject."
David Gubbins, 56, is research professor of earth sciences at Leeds Uni- versity. He mapped the earth's magnetic field and led the first field project using seismometers to provide data of the same quality as that from permanent observatories.
"It's still possible to make big discoveries - a fossil in an unexpected place or a wiggle on a seismogram indicating a new subterranean structure."
David Price, 47, is professor of mineral physics at UCL and Birkbeck College, London. He established the computer modelling of minerals, based on atom structures, and provided the first estimates, based on quantum mechanics, of the temperature and composition of the earth's core.
"I have always looked to apply methods from physics and chemistry to solve problems in geology."
Steve Larter, 50, is professor of geology at Newcastle University and set up its research institute for petroleum and environmental geochemistry. Best known for developing chemical techniques to determine oil field drainage, he won the Geological Society's William Smith Medal in 1998.
"Geology captures the excitement of all the recent scientific revolutions, and the scenery is pretty good too."
Sir Nicholas Shackleton
Professor Sir Nicholas Shackleton, 66, works on the history of climate and was one of three scientists who advanced research to support a theory for Ice Age fluctuations based on the earth's orbit patterns.
"I love the challenge of putting together climate records from materials such as ocean sediments, polar ice sheets and peat bogs to improve our understanding of the earth's climate. …