Map of Forest and Grassland communities as they existed 5,000 years before the present. As important, all the elements that exist in today's forests surrounding the Great Lakes and across New York State were all present. These were the Mixed Coniferous-Hardwoods, the Oaks and Hickories, and the rich and diverse Mixed Hardwoods. Map of Forest and Grassland communities as they existed 2,000 years before the present. The work of piecing together this chronology of events has been long and tedious.
Pollen grains have two very important attributes.
First they are very resistant to decay, especially is places where there is little or no oxygen. Such places are bogs and lake bottoms. Second each plant genus, and frequently each species, has pollen that has distinct characteristics that allow it to be identified positively. Pollen is shed each time that a plant flowers and much of it falls to earth. Where ever it falls in oxygen poor areas such as bogs and lakes it becomes incorporated into the peat or the sediment.