This tour guide for the northern part of Ireland was born out of an earlier version prepared by the Geological Survey of Northern Ireland and the Geological Survey of Ireland at the request of the Geological Society of London in support of the Society's bicentennial celebrations in 2007. The diverse age of rocks present in the northern part of Ireland commence in the Palaeoproterozoic (about 180 million year old) and include representatives of all the systems up to and including Palaegene (60-25 million years old). Geology does not stop at political boundaries and the regional geological maps published by the Surveys show the continuity of major geological structures and lineaments that dominate the geology of Northern Ireland into the Republic of Ireland.