The article discusses how scientists studied layers of volcanic ash in the seabed around Iceland to understand past volcanic activity. They found 130 ash layers in sediment cores dating back 15,000 years, with most on the North Iceland shelf. The Saksunarvatn and Vedde Ash layers were found across all shelf areas. By comparing these ash layers to those on land, they could date events and track environmental changes. The ash layers also helped estimate marine reservoir age and reveal volcanic activity history. This research shows the value of marine ash layers for dating, linking land and sea records, and studying Icelandic volcanoes.