Current Interglacial - Changing Plant Communities:
Our picture of environmental change over the past 12,000 years is more detailed than for earlier times. Scientists have more evidence and more types of evidence to analyze. Clues still come from fossils, soils, and sediments. Archaeological sites are also full of important clues. Beginning in 1673, explorers left written records describing the Illinois environment.
Fossil Evidence: Pollen
Fossil pollen shows a rapid change from spruce to deciduous forest 11,700 years ago. It also shows an initial decrease in pollen from deciduous trees around 8,000 years ago, and a change from deciduous forest to prairie and oak groves 6,500 years ago. All of these changes were climate related. Environmental changes caused by people—the expansion of agriculture, logging, and the plowing of the prairie after European settlement?are also evident in pollen records.