Although recent discoveries and exploitation in the South Atlantic have re-emphasized their importance, for many years, lacustrine carbonates have been de-emphasized relative to their more abundant open marine counterparts. Seventy-five years ago, Twenhofel described bottom sediment in Lake Monona in Wisconsin. The study of cores from this lake revealed black organic-rich sludge underlain by lighter-colored firm marls. Perhaps heralding recent emphasis into the importance of microbial processes in lacustrine carbonates, the results were interpreted to reflect the importance of bacteria in degradation of organic matter, precipitation of calcium carbonate, and, ultimately, the manner and style of accumulation of these lake deposits.
The Bottom Sediments of Lake Monona, a Fresh-Water Lake of Southern Wisconsin by William. H. Twenhofel