The size distribution of charcoals in sediments of Lake Michigan reflects the onset of the industrial revolution and the increased intensities of fossil fuel combustion during the twentieth century. Prior to 1900 the less than 1 microns fraction was dominant, and its source was primarily biomass burning. In the subsequent years coal and oil burning became evident with larger particles, especially greater than 32 microns, making larger contributions to the total charcoal concentrations. The input of the larger particles is a consequence of near fallout of particles from energy-producing plants near the lake.