Another Life: The mountain summits and high plateaux of Ireland's hills can be bleakly forbidding places. Rather than the smooth contours that distant views suggest, the peat is weathered into stark, black "haggs" - sooty masses of peat, often shoulder-high, separated by glistening black gullies, pools and stretches of gravel, writes Michael Viney.
I once pitched a tent overnight on top of Mangerton Mountain in Co Kerry, it was like camping on a waterlogged moon.
This dramatic high-level erosion is nothing new. Trinity botanists have dated its beginnings from peat cores. In the Wicklows, it started around 3,000 years ago and in Co Donegal perhaps half that. A few centuries of grazing and trampling by people and animals may have stepped up the recent rate of erosion, but they were not the initial cause. As peat accumulates in wet mountain areas, the scars from natural bog flows or the collapse of sub-surface pipes open the bog to erosion by lashing rain and by winds that blow most fiercely at the highest contours.
On the tops there is no protection from any quarter. Further down, however, the wind is shared between the hillsides and so drops in speed. Here, in undisturbed conditions, begins the deep-rooted vegetation of heather and moorgrass, a tough, closely woven skin to the peat. As water rushes off the high plateaux, these plants slow it and soak it up, steering the surplus to streams and waterfalls in the folds of the hillside.
At the base of the hills there could still be natural "bog bursts", as heavy rainfall swelled a "lens" of water trapped between different densities of blanket bog. As the lower edge of the bog burst open, its upper mass of peat was propelled, sometimes for miles, over the land and houses below. But on the higher slopes, a tough corset of plants generally held the thin, peaty soils in place.
With wiry, woody stems and narrow, folded-down leaves, heathers are adapted to survive drought and wind. Old plants shelter dozens of lichens and liverworts that help to cover the peat surface and are equally able to survive dry weather. In the over-grazing of the late 20th century, the heather was the first to disappear. Then the moorgrass, Molinia, was depleted, leaving islands of bare peat between the tussocks until the coarse mat grass, Nardus stricta, which even sheep wouldn't eat, spread slowly in its place.
Andrew Bleasdale, the botanist whose research in Connemara has underpinned much of the current reform of upland management, recorded memorable images of
"starving sheep and vast expanses of bare peat" in the 1990s. Today, on protected hillsides in the Connemara National Park, knee-high heather bears witness to what has been lost outside the fence.
A landscape so badly degraded will take decades to repair. And now its slow recovery has been overtaken by two alien climatic factors in the western upland ecology - prolonged summer heat and drought, and rain delivered in localised torrents from super-saturated clouds.
A whole decade ago, the first studies on the implications for Ireland of climate change warned of "gradual shrinkage" and decay of the peat of upland blanket bogs, and erosion by intense rainfall. That summer drought would open up great cracks on threadbare heights and that unbelievable gouts of water and rock debris could shred the thin and fragile skin of whole hillsides was nowhere in the scenario. But the deterioration of peatlands was seen as "possibly the most deleterious outcome of the climatic scenarios in Ireland" and one that seemed to be "without a technical remedy". As UCD's Dr John Feehan, co-author of The Bogs of Ireland, says, peatland which has taken thousands of years to form "may disappear within a generation".
How much of what I have described is borne out by the north Co Mayo landslides must wait on the technical results of investigation by geologists, hydrologists, meteorologists, soil scientists, botanists and bog specialists.
The role of over-grazing, if any, will need to be interpreted in a wider and more sympathetic context than the particular farming history of the unfortunate communities of Pollatomish and Glengad.
Five thousand years ago, the Neolithic farming settlers of north Mayo cleared the pine forests of the hillside. When the climate got wetter, the minerals of the exposed soil were leached down into an impermeable
"iron pan". This led to waterlogging of the thin hillside soil and the growth of bog. It also provided a surface on which a hillside could slide if lubricated with enough water.
Climate has changed again, this time by human agency, and the behaviour of ocean rain is once again the key to the future of the western hills and their human communities. The deluge in Co Mayo was but an extreme local demonstration, as a warming and evaporating ocean is drawn up into the sky.