The Chattanooga shale contains insoluble organic matter (kerogen) derived from terrestrial (humic) and from marine (sapropelic) sources. Kerogen from sapropelic sources contains more hydrogen than kerogen from humic sources. Thus the hydrogen content of the sapropelic contribution, and of the kerogen, increases toward that part of a shale most likely to be a source bed for petroleum. Uranium in the shale is derived from the adjoining land mass.
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Breger et al. (1962) studied this question.