Another classification according to the type of kerogen, is based on the hydrogen, carbon, and oxygen content of the original organic matter in the oil shale. This classification is using the Van Krevelen diagram. The most used classification of oil shales was developed between 1987 and 1991 by Adrian C. Hutton of the University of Wollongong, adapting petrographic terms from coal terminology. According to this classification, oil shales are designated as terrestrial, lacustrine (lake-bottom-deposited), or marine (ocean bottom-deposited), based on the environment where the initial biomass was deposited. Hutton's classification scheme has proven useful in estimating the yield and composition of the extracted oil.