Underlying the spectacular, rugged beauty of CORCA DHUIBHNE, the Dingle Peninsula, a stony core of rock records a fascinating saga of earth history going back at least 410 million years to the Silurian Period. The earliest chapters in this story reveal the presence of a shallow sea where small colonial corals, brachiopods and trilobites lived on a soft bottom of fine sand and mud. After a few million years, shifts in the earth's crust uplifted CORCA DHUIBHNE, and the sea withdrew. Following a period of crustal instability, erosion, and volcanic activity, CORCA DHUIBHNE next emerged as a vast inland valley basin bordered by uplands and mountains.
The lakes of Kerry in the mountainous regions are numerous, but few are of large dimensions. The most remarkable, both for extent and beauty, is the celebrated Lough Leine, the principal of the lakes of Killarney, three in number, which are connected by straits, or short rivers. They are distinguished by the names of the Upper, the Torc, and the Lower lake. There were two O'Donoghue septs, namely, clans. One was O'Donoghue Mor, whose home was Ros Castle on Lough Leine right outside of Killarney (Irish: Cill Airne, meaning "The church of the sloe") . The other Donoghue clan was "The O'Donoghue" of Glen Flesk or Kilaha subsisted longer than the O'Donoghue clan at Ros. The clan lands were in the "Glenn" some seven miles west of Killarney. Of these the principal are O'Donoghue of Desmond, O'Donoghue of Uí Maine (Hy Many) and O'Donoghue of Co. Cavan.
Killarney is home to St. Mary's Cathedral, Ross Castle, Muckross Abbey, torc waterfall and Innisfallen Island, the location of a ruined monastery. It is a sister city of Concord, North Carolina.
There is no other landscape in western Europe with the density and variety of archaeological monuments as the Dingle Peninsula. This mountainous finger of land which juts into the Atlantic Ocean has supported various tribes and populations for almost 6,000 years. The southwest of Ireland has traditionally been seen as having few Neolithic monuments. The Loch a'Dúin valley near Cloghane contains the most remarkable series of monuments from the Bronze Age. In this valley of 1,500 acres, there are 90 stone structures dating from 2500 BC up to modern times.
Running like a web throughout the landscape are several miles of stone wall, hidden by peat which has accumulated over the past 3,000 years. Loch a'Dúin Valley was used for intensive agriculture, both pastoral and arable, from 1600 BC to the beginning of the Iron Age.