Sediment cores are cylindrical samples taken from the bottom of lakes, oceans, or other bodies of water. They provide a record of the layers of sediment that have accumulated over time, allowing scientists to study past environmental conditions, climate changes, and geological events. Each layer represents a specific time period, capturing information about the Earth's history. Researchers extract sediment cores using specialized equipment, often drilling into the sediment. The cores are then analyzed for various properties, including pollen, microfossils, and chemical composition. This analysis helps scientists understand ecological changes and the impact of human activities on the environment over thousands of years.