Lawrence Alexander Hardie (January 13, 1933 – December 17, 2013) was an American geologist, sedimentologist, and geochemist .
Hardie was a professor at Johns Hopkins University in the Department of Earth and Planetary Sciences. His research topics included evaporites, dolomitization, cyclical deposition of carbonate sediments, and plate tectonic driven changes in seawater chemistry. In the latter, he proposed that changes in the seafloor spreading rates at mid-ocean ridges have altered the composition of seawater throughout earth history, producing oscillations in the mineralogy of carbonate and evaporite precipitates. Specifically citing these scientific contributions, the Society for Sedimentary Geology (SEPM) awarded him the Francis J. Pettijohn Medal in 2003.
Early life and education
Hardie was born in Durban, Natal, South Africa, on January 13, 1933. He attended the University of Natal, Durban, originally to pursue an undergraduate degree in chemistry. He focused instead on geology after attending lectures by South African geologist Lester Charles King. While a student, Hardie played soccer, and was selected as a member of the South African Universities "All Star" team four times. He earned a B.Sc. degree in Geology and Chemistry in 1955, and a B.Sc. (Hons.)degree in Geology in 1956.
In 1957, he was hired by King as an instructor and taught beginning classes in geology while working on his master's thesis on the origin of the Table Mountain Sandstone. He earned an M.Sc. in geology in 1959 under the guidance of Drs. Peter Matthews and Joseph Frankel.
In 1960, he was awarded a fellowship by the South African Council for Scientific and Industrial Research to spend an academic year in the U.S. He went to Johns Hopkins University and began working with sedimentologist Francis J. Pettijohn and geochemist Hans Eugster, in a newly built geochemistry laboratory. There he conducted experimental work on evaporite minerals. He was offered a full-time graduate fellowship to earn a Ph.D. He briefly returned to South Africa to marry Glenys Kathleen Smith in Durban, and then graduated with a Ph.D. in 1965.
Academic career
Hardie joined the faculty at JHU as an assistant professor in the Department of Earth and Planetary Sciences in 1965. He later became a full professor, mentoring more than 30 graduate students. He also taught introductory geology to many undergraduate students, including his own children, introducing them to the intricacies of geological process through extensive field trips. He also served as the department chair from 1992 to 1995, and again in 2004–2006. He retired in 2007 to the status of professor emeritus.
Hardie ran the JHU field camp (Camp Singewald) in western Maryland for many summers in the 1960s and 1970s. He led regular field trips to the Florida Keys and Assateague Island, and also took students to the Bahamas and Baja California, Mexico. His work also took him frequently to the Dolomites in Italy, and he partook in long hikes and climbs. Some of his field work required travel by Zodiac inflatable boats, minibikes, and 3-wheeled all terrain vehicles.
Scientific achievements
Early in his career, Hardie conducted research and experimentation with evaporites. Later he showed that the signal from evaporites provides evidence for seawater chemistry change. He observed that secular changes in the mineralogy of potash evaporites and ooids and cements in marine limestones are synchronous with greenhouse/hothouse climates and global sea level. Hardie's study of evaporites led to the hypothesis, since verified through study of seawater trapped inside crystals of marine halite, that seawater has undergone long-term variations in its major ion composition. He demonstrated that these variations are linked to plate tectonic processes at mid-ocean ridges. These studies improved the understanding of calcifying marine organisms and their role in the global carbon cycle, and also had implications for geochemistry, mineralogy, tectonics, biological evolution (biomineralization), oil/gas resources, and climate change. In recognition, he was awarded the Francis J. Pettijohn Medal for Excellence by the Society for Sedimentary Geology in 2003.