astronomy

Lawrence Alexander Hardie

Lawrence Alexander Hardie is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lawrence Alexander Hardie rather than just read about it. In short: 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.

Key takeaways

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Reference excerpt

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. Hardie completed field research on the modern shallow marine carbonates of the Bahamas with Bob Ginsburg and others. In 1977 he wrote a book on comparative sedimentology entitled Sedimentation on the modern carbonate tidal flats of northwest Andros Island, Bahamas. He went on to study ancient carbonates of western Maryland (Cambro-Ordovician) and the Italian Dolomites (Triassic). Hardie's work on carbonates advanced the understanding of climate and sea level change, and the role of Milankovitch cycles in carbonate deposition. Another of Hardie's contributions involves the study of the origins of dolomite, a mineral associated with the world's oil reserves. When dolomite replaces calcite minerals, its slightly smaller molar volume leaves voids in carbonate rock, causing oil migration. In the Italian Dolomites, Hardie (with student Edith Wilson) demonstrated the hydrothermal origin of dolomite in the Triassic Latemar buildup. Hardie and his students and colleagues also studied cyclic sedimentation, confirming that platform carbonates of the Middle Triassic (Anisian-Ladinian) of the Latemar buildup consist of a vertical stack of over 500 thin (ave. thickness 0.6-0.85m) shallowing-upward depositional cycles that record high frequency eustatic sea level oscillations in tune to Milankovitch astronomical rhythms. They described the details of the cycles and deposition and created computer simulations that accurately modeled the Latemar cyclostratigraphy using Milankovitch-controlled sea level oscillations.

Awards and honors

Francis J. Pettijohn Medal for Sedimentology, from the Society for Sedimentary Geology, 2003. Selected by the Student Council of Johns Hopkins University as one of the top ten teachers in the School of Arts & Sciences in 1998. Oualline Distinguished Scholar at University of Texas, Austin, 1995. The "Hardie Teaching Laboratory", in Olin Hall at JHU has been dedicated in 2014. One of the annual Krieger School's Dean's Undergraduate Research Awards at JHU has been named after him, 2014. The Lawrence A. Hardie Memorial Fund in Earth and Planetary Sciences at JHU, 2014. Lawrence A. Hardie Commemorative Session, Geological Society of America meeting in Baltimore, MD, November 1–4, 2015.

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Illustrations

Worked examples

Example 1 — a first encounter with Lawrence Alexander Hardie

Start with the simplest possible case. Write down what Lawrence Alexander Hardie claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lawrence Alexander Hardie before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lawrence Alexander Hardie ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lawrence Alexander Hardie

In research: Lawrence Alexander Hardie appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lawrence Alexander Hardie in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lawrence Alexander Hardie is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1933 births, 2013 deaths, American geochemists, so understanding it makes those chapters shorter.
In everyday life: Look for Lawrence Alexander Hardie outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Lawrence Alexander Hardie in 20 minutes

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Frequently asked questions

What is Lawrence Alexander Hardie in simple terms?

Why does Lawrence Alexander Hardie matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lawrence Alexander Hardie?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lawrence Alexander Hardie.