These small glass shards may not look like much, but this microscopic volcanic ash can provide immensely important age estimates for the peat sequences we work with. Each group of shards belongs to a different volcanic eruption and it is possible to tell the difference between them based on subtle variations in shape, colour and, perhaps most importantly, their chemical makeup. You can learn more about tephrochronology – the practice of dating sediments using volcanic ash – by clicking here.