Sediment cores are cylindrical samples of sediment that are extracted from the ocean floor, lake beds, or other bodies of water. These cores provide valuable information about past environmental conditions, such as climate change, ocean circulation, and the deposition of pollutants. Scientists analyze the layers of sediment within the core to study changes in sediment composition, grain size, and chemical properties over time. Sediment cores have been used in a wide range of research fields, including paleoclimatology, paleoceanography, and environmental science.