[1] His research topics included evaporites, dolomitization, cyclical deposition of carbonate sediments, and plate tectonic driven changes in seawater chemistry.

[2] 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.

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 went to Johns Hopkins University and began working with sedimentologist Francis J. Pettijohn and geochemist Hans Eugster, in a newly built geochemistry laboratory.

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.

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 1977 he wrote a book on comparative sedimentology entitled Sedimentation on the modern carbonate tidal flats of northwest Andros Island, Bahamas.

When dolomite replaces calcite minerals, its slightly smaller molar volume leaves voids in carbonate rock, causing oil migration.

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.

[4] They had two children; his daughter Deborah obtained a degree in mathematics at JHU, and Russell studied engineering at Loyola University Maryland.