Discrete layers of tephra have been found in both raised and blanket bogs in the north of Ireland. Some of the layers have been identified to an Icelandic source and, in two cases, specific eruptions of known radiocarbon age are suggested. Nine layers spanning the Holocene are replicated in three lowland raised bogs. One of the major layers has also been identified at a number of sites in two separate upland blanket peat systems and in a lake sediment.