Tourist Guide

Rising abruptly above the low coastal plain near Sligo Bay in north western Ireland are the Dartry Mountains, a series of impressive, flat-topped massifs bounded by spectacularly steep slopes which are popular for walking holidays. The westernmost of the group is Benbulbin, which reaches 1,722 feet (525 meters) above sea level. (Ben is the Gaelic word for mountain.)

Bleak, austere, frequently battered by storms that sweep in from the Atlantic, the great plateaulike mass of rock has always had the power to stir the imagination. According to legend, it was a dwelling place of the Fianna—bands of warriors who flourished in the third century A.D. Since that time they have been heroes of Irish folklore, and their names and exploits are evoked in the verse of the famed lyric poet William Butler Yeats. Yeats, who loved this countryside, is buried in a cemetery in the village of Drumcliff at the foot of the mountain.

Benbulbin is a huge block composed of horizontal layers of sedimentary formations that were deposited here about 320 million years ago. The nearly straight-walled, furrowed cornice at the top of the mountain includes thick beds of two limestone formations: the massive, light-colored Dartry limestone on top of the thinner, darker Glencar limestone. The gentler lower slopes, largely mantled by debris, are composed of much softer Benbulbin black shale.

The mountain’s particularly distinctive cliffs were sculpted by glaciers during past ice ages, which alternated over hundreds of thousands of years with temperate interglacial periods. At their greatest extent, massive ice sheets covered nearly all of Ireland and Great Britain. Their modeling action resulted not only from grinding by debris as the ice sheets slowly advanced, but also from the powerful runoff of melt water when the glaciers retreated.

The remains of spectacular landslides can be seen in nearby valleys, while a smaller but nonetheless impressive landslide has scarred Benbulbin’s north western face. That dramatic wall of stone, directly exposed to the full violence of ocean storms, is also corrugated by deep, evenly spaced vertical channels, apparently caused by both abrasion and dissolution of the limestone.

More sheltered and less rugged, the south western and north eastern sides of the mountain permit easy access to the flat summit. At the top of the mountain the surface is a patchwork of peaty areas covered by dwarf, windblown heaths alternating with coarse rubble.

Several arctic-alpine plant species, which are relics of ancient glacial periods, thrive in hollows in the limestone on the mountaintop. Normally found in colder climates much farther to the north, these species extended their ranges southward during the ice ages. Then, as the glaciers retreated and the climate warmed again, they managed to survive only in the cooler habitats found at high elevations.