Camross Pingos - Legacy of The Ice Age


MICHAEL DOYLE

Many readers may ask what on earth are pingos. People in the Camross/Caroreigh end of Taghmon parish may have heard of them, but they are still very hazy as to what they are and what they represent. In this article I hope to throw some light on this specific land formation, which came about as a result of activity which occurred during the Ice Age, which covered Ireland in the region of two million years ago.

'Pingo' itself is an Eskimo word and is described as an arctic mound or hill, shaped like a volcano, consisting of an outer layer of soil covering a core of solid ice. These features are common in the Arctic /Eskimo regions of the world today. What we have here in Camross are the remains of what once fitted the above description. Of course, with the ice core long melted, the central mound has subsided and we are left with a collapsed centre surrounded by a raised rim of land forming a circle or partial circle.

These land structures - fossil pingos- were first identified in the Camross area in 1969, by Professor Frank Mitchell, of Trinity College Dublin. The assumption was, that if pingos were quite common in arctic regions at present, the probability was they must have occurred in parts of Ireland when we had similar climatic conditions to the arctic today.

The Pingos were first identified from the air, and Professor Mitchell and his surveying party spent the summer months of 1971 in Camross analysing and documenting them. He published the results of his findings in November 1973 in a booklet from the Royal Irish Academy entitled 'Fossil Pingos in Camross townland, Co. Wexford.' '200 structures believed to be fossil pingos are recorded in the study area. The main road from New Ross to Wexford in south east Ireland runs through Camross townland at an altitude of 70 metres (225 feet). The local rocks are slates and sandstones of Ordovician age containing contemporary volcanic rocks. The area was strongly effected by the Caledonian folding movement. Denudation has produced a 'surface' at about 60 meters (200 ft) on the sedimentary rocks above which rise the more resistant volcanic rocks.

In the North of the townsland a boss of quartzporphry rises to 180 metres (600 ft) to form Camross Hill. The area was glaciated in the late phase of the Munsterian Cold Stage when ice coming from the Midlands passed over the area in a south easterly direction. The area was not glaciated in the Midlandian Cold Stage, although, ice of that age, advancing westwards from the basin of the Irish Sea only halted at Tomcoole cross-roads three kilometres south-east of Camross.

In a limited area, North east of Camross, fossil pingos were particularly prominent . Here it is assumed that a pingo is formed when water which has been forced upwards by freezing pressure, itself freezes in a lens like form near the surface of the ground arching the surface layers up over itself and forming an earth covered ice-cored mound .

When thawing sets in, the surface layer thaws first and slumps down off the ice-core building a rim of earth round the core. This material is transferred from the central area to the perimeter and, when the core melts, a hollow will be left at the centre, surrounded by the raised rim, which contains the transferred material. In an ideal case slumping will have taken place evenly around the core and the subsequent rim will form a complete circle. But slumping may have been uneven, or there may have been subsequent collapse and the rim may be incomplete forming only an arc of a circle' .

The remains of this process so many, many years ago is still with us to this day in the Camross area and it is remarkable that after thousands and thousands of years, evidence of the Ice Age remains on in our local landscape.

The fossil pingos vary greatly in size from small circular hollows to structures as big as 75 meters (250 ft) in diameter. Many of the larger ones have (or had before drainage) floating masses of vegetation while the smaller ones formed part of cultivated areas without any hindrance.

One notable aspect in the existence of fossil pingos is that they all occur on poorly drained soils and where the soil is well drained, pingos cease to exist. As already mentioned they are particularly prominent in an area north east of Camross, on the right hand side of the Oldtown road, as one travels from Camross to Adamstown.

They continue along the valley, where they cease, on entry to a vast area of marshland, known as the 'black bog'. South eastwards from here a section of well drained soil arises but beyond that, where the soil is again poorly drained, pingos appear in quantity.

On the south side of Camross these structures continue on a gently sloping floor towards Caroreigh, but disappear again, when converging flanks of well drained soil appear. Again quoting from Professor Mitchell, he says 'a poorly defined ridge of higher ground links Camross to Wattle Cross-roads (cross of the wobble). The soil on the ridge is poorly drained and a few pingos can be traced across it. An embayment of flattish land lies on the floor of the valley west of Camross and big pingos also occurred here. West of Wattle cross- roads the slope is again very gently and numerous pingos spring from the floor of an embayment which lies between 60 and 65 meters (200- 210 ft).'

Locally, pingos, before they were authoritatively identified, were known as 'bog holes' and 'ponds' and one, in particular, was known as 'the cat and dog hole'. Many believed that they were dug out of straight earth in the last century to build mud and clay houses. Professor Mitchell and his team concluded, by technical examination into the floor bottom of some of the larger pingos, that they had been disturbed in the early nineteenth century, and they contained peats and muds dried and used for firewood. However, he found one pingo which contained a small amount of open water mud at the base, which was undisturbed organic material.

Samples for pollen counts and macroscopic examination were taken. Results from the pollen count show that, at a depth of 110 cm. in the sandy clay loam, the open characteristic of the last Ice Age was in evidence. Above that, the overlying mud showed the establishment of post glacial grasslands, followed by the appearance of Juniperus and Betula. Juniperus are evergreen trees and Betula is of the birch tree family. Thus, we can see the undoubted influence that the movement of ice has had on our local landscape.

This influence has also happened in other areas. For example, we know that pingos occur south of a line from Arklow to the Shannon Estuary and in northern latitudes around the world.

In the 'Shell Guide to the Irish Landscape' there are three very interesting photographs in the chapter dealing with the ice age. One shows a modern pingo in its frozen state in the arctic region of Siberia. The second shows a collapsing pingo in a less colder area of the North west Territory of Canada and the third photograph shows the fossil pingos that we have here in Camross today. We have only reached this fossilised state by going through the processes which are presently occurring in Northern Arctic regions.

The formation of pingos was not an isolated activity during the time of the Ice Age. In fact, this era witnessed other upheavals and movements in the earth's surface. Further evidence of these can be seen today in the landscapes of the parish of Taghmon.

In his book 'The Landscape of South Wexford', Dr Edward Culleton says that the deep channel running from near Growtown through Brownscastle to Mulmontry bridge was cut through the solid rock from a decaying ice sheet. He goes on to state: 'The exact origin of this meltwater channel is not clear. It may be the original course of the Slaney which, blocked by a glacier to the south and the east and powered by meltwaters from an ice cap on the Wicklow mountains, cut its way through the shale bedrock to form this steep sided channel. Alternatively the channel may have been cut by meltwaters from the Irish Sea glacier escaping eastwards.

Some evidence is provided for this by the "erratics" such as flint in the glacial deposits at Mulmontry further west.'

We can see from this that the structure of the land in Brownscastle today is another fine example of what melting ice did, as it cut its ways through the ground forming a deep gorge powered by continuous melting ice behind it. Other examples of meltwater channels in the county can be seen at Poulmounty, Taylorstown, Carrigmannon, Kilcotty and Ferrycarrig.

Dr Edward Culleton also refers to the 'Caledonian Folding movement' by which, professor Mitchell says, the area was affected. This, Dr. Culleton says, was a series of convulsions in the earth's surface, probably lasting millions of years and causing the crust to crumble long before the ice came.

Camross Rock is one of a series of volcanic rocks running from Duncannon, in south west Wexford, to Kilmichael Point, in the north east of the county. Others include Carrigbyrne, Bree and Vinegar Hills. According to Dr. Culleton, this happened during the Ordovician age which was also referred to by Professor Mitchell. The Ordovician period occurred around 430 million years ago. Dr. Culleton goes on to say: 'these volcanic rocks emerged from small underwater volcanoes pushing molten material up to the surface. This solidified to form hard rocks which have resisted breakdown by weathering agents to the present day'. This includes the ice sheets which spread glacial drift - a mixture of boulders, clay, sand and gravel - over the areas where we now live and indeed throughout much of County Wexford.

All of this activity helped to form the fertile farmland which we now use to great benefit.

So whether it is pingos, meltwater channels, or the very soil that we cultivate, they all form part of the great legacy left to us by the Ice Age, which happened in the dim twilight of long, long ago.

FOOTNOTES

  1. The World Book Dictionary
  2. Pingos in Camross Townland, Co. Wexford Published by Royal Irish Academy 2 Nov.1973
  3. Shell Guide to Irish Landscape: Country House Publications-1986