IGH12 - Mesozoic and Cenozoic Theme
This theme is a limited one for the simple reason that rocks of this age are rare in the Republic of Ireland. Much of Antrim has rocks of Jurassic and Cretaceous age as well as the Tertiary basalts best displayed at the Giants Causeway, but the panels for this theme will mainly consider only very rare deposits in a limited number of geological settings. The reason for this is that during much of the Tertiary period and since, erosion has removed any deposits of these relatively young rocks if they were ever deposited.

This has been a topic of much research in the geological community over recent years, and many new approaches are being applied to understand the evolution of the Irish landscape over the past 200 million years. This means that the few sites that preserve rocks proven to be of this age, from the microfossils included in them, should be carefully assessed. Where necessary the best sites should be protected as NHAs to enable ongoing research to answer these questions.

Most of the relevant sites are thought to be karstic depressions (dolines) or caves, such as Ballygiblin in County Cork where sediments have been preserved from sustained erosion. Ballydeenlea, near Killarney in County Kerry is one of the most famous as it includes Chalk deposits (widespread over southern and eastern England) otherwise only found in Northern Ireland. Did a Chalk sea once cover Ireland? Protecting sites such as this is the only way to allow answers to be found in the future.