The Vedde Ash, a volcanic ash layer from Iceland around 12,100 years ago, is important for dating in the North Atlantic and Europe. Scientists studied marine sediment cores to identify the original Vedde Ash layers. They used various methods like visual inspection and chemical analysis to distinguish primary ash deposits from reworked ones. They found two layers from the Katla Volcanic System and two from the Veidivotn-Bardarbunga System. The ash layers show a mix of basalt and rhyolite, indicating the Katla layers as the Vedde Ash. The study also estimated the temperature and water content of the ash before the eruption, suggesting a complex process of magma mixing. This research helps us understand how volcanic ash deposits form and can be identified in sediment cores.