The Mesolithic in Ireland is regarded as that period from around 8000 - 4000 BC which started with the arrival of the first settlers in Ireland following the retreat of the ice sheets. In this post-glacial phase, with an improved climate, dense woodland cover and an increasing population of wild fauna, the first settlers would have found a suitable habitat to accommodate their hunter gatherer lifestyle, though unlike the UK and Europe, more limited as larger mammals such as wild cattle and deer were not present in Ireland.
Up to the 1980s Archaeological evidence for the mesolithic predominantly came from the North East and East coast. Since then excavations including Ferriter's Cove in Co Kerry, Belderig in Co Mayo, Lough Kinale and Killuragh Cave show there was Mesolithic activity throughout the country. However as Peter Woodman commented in a 2006 paper (The Irish Naturalists' Journal, Vol. 29, Special Supplement) for the 4000 years of the Irish Mesolithic there are relatively few substantial, adequately excavated and published sites on the whole island that can provide real insights into the longest single period of human settlement in Ireland.
The first evidence of human settlement in Ireland dates to around 8000 BC. This date comes from the Mount Sandel site in the north of the country which represents the earliest known certain occupation site in Ireland for what is described as the early Mesolithic. The microlith, small flint tools likely to have been set in bone or wood for use is the dominant artefact type of the early Mesolithic found in the archaeological record in Ireland.
Mesolithic sites dated to 6000 BC and later display a change in their stone working technology producing bigger single piece artefacts. This change is characterised by leaf shaped flakes of flint unique to Ireland often called Bann flakes as a large amount have been found in the Bann valley. This period known as the Late Mesolithic is sometimes referred to in the older literature as the Larnian phase.
Around 4000 BC sees the end of the Mesolithic with the adoption of agriculture in Ireland, the start of the Neolithic.