What does a research scientist do when retirement threatens to bring a lifetime of study to a halt? Ignore it and keep on researching, in the case of Prof Charles Hepworth Holland.
An emeritus fellow of the department of geology at Trinity College, Dublin, he was one of the last academics allowed to step down at 70, a milestone he passed eight years ago. Not having allowed retirement to end his work, Hepworth most recently launched The Geology Of Ireland, an extensively illustrated definitive study, which he edited. Holland also continues his examination of the life forms fossilised in outcrops across the island.
"I am working very much on palaeontology," he says. "I have published about eight times last year. I work on a group of molluscs, the so-called cephalopods. They are old relatives of the nautilus."
His main research focus is on the Silurian period, about 420 million years ago, which falls within the Palaeozoic age. In particular, he studies the stratification of rock on the basis of its fossil content. "The best way of tying one place with another in terms of time is the fossils. You can recognise time in this way," he says.
This type of analysis has uncovered strange things about this island and its ancient rocks. It shows that we are at once part of North America and Europe in terms of our geological history, with the north-west representing a piece of America and the south-east a piece of Europe.
The fossil and rock record divides the island diagonally, says Holland. "The line would emerge near Dingle, right through to south Co Down. It is not obvious, this line; it is a refinement."
Such a division is possible because, 400 million years ago, Ireland lay across a subduction zone, in which the part of the earth's crust on which North America now sits was sliding underneath the part that now supports Europe.
The geology is not immediately apparent, particularly as the mid-Atlantic rift where new crust is today being formed is slowly pushing America away from Europe. "In the Palaeozoic, there was an entirely different set-up," he says.
Some evidence of Ireland's split geology is visible in the rocks, but this can be misleading, says Holland, as similar types of rock can be found on both sides of the divide. The proof lies in the creatures that lived and died during the Palaeozoic, and whose fossil remains can be found deep in the stones.
A similar split can be seen in other parts of these islands, he says. North-west Scotland has fossils of trilobites that match species discovered in North America. Yet trilobites more typical of those found in Continental Europe have been recovered in Wales, he says.
Holland came to Trinity in 1966, from the University of London, to take the chair of geology and mineralogy. He had no connections with Ireland, although he had done field work in Dingle. "I found it a bit more different than I expected," he admits.
He remained, however, and went on to develop a deep appreciation of the island's geology and the scenery that crowns it. "It is a wonderful geology that is rich in variety."
He was involved in a preceding examination of what lies underfoot, A Geology Of Ireland, published in 1981. The new book is very different, however, which is why "The" was substituted for "A".
"It is not just a second edition," he says. It contains much new material, is about twice as long and includes full academic references. Its style makes large parts of the book accessible to the interested beginner, but it will also serve the professional geologist, he says.
The Geology Of Ireland, edited by Charles Hepworth Holland, is published by Dunedin Academic Press, £105 hardback, £55 paperback
