Current interests are: processes (including biomineralization) associated with the formation of microbialites (dendrolites, stormatolites, thrombolites); the roles of algae and fungi in the formation and alteration of ooids, especially marine ooids; karst and paleokarst; paleokarst as an indicator of tectonics; paleosols in carbonate sediments and rocks; freshwater carbonates in Permian rocks in the Colorado Plateau; carbonate-evaporite tidal flats; Silurian reefs in the Great Lakes region, especially thrombolite reefs and microbialite-coral reefs; nature and significance of the spacing of tabulae in Favosites in Silurian microbialite-coral reefs in western Ohio; origin of cement fabrics in dolomites; recognition and significance of fabrics brought about by the freshwater alteration of dolomites; syntectonic sedimentation; origin of fabrics in travertines; did El Nino-like events take place during the Silurian in the Michigan basin?