Paleogeographic reconstruction in parts of the Carboniferous of western Pennsylvania have shown that an average paleoslope of three feet per mile is sufficient to markedly affect the thickness, continuity, and geochemistry of a freshwater limestone. Compared to limestones deposited on topographic highs, those deposited in lower areas are thinner, more discontinuous, contain greater amounts of siderite and dolomite, lesser amounts of calcite, and have more negative delta C-13 values. These differences are attributed to the sizes and depths of inferred lakes, factors which control rate of circulation and evaporation.

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