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Waterford Geology

Waterford Geology and Prehistoric Dungarvan

2. Waterford Geology

The basic geological structure of the area differs along a north-south line slighly to the east of Dungarvan. To the east of this line the older Ordoirican rocks 400 to 500 million years old and Siluvian rocks of similar date. To the west of the line lie the Devonian rocks 350 to 400 million years old from the highlands running to east-west folds as far as kerry. These were originally overlain with carboniferous rocks 310 to 350 million years old which have long since been eroded from all but the low lying valleys. The valley running westward from Dungarvan to Cappoquin contains this carboniferious limestone in numerous caves have been formed.

It was not until comparitively recently, at the begining of the Pliocene Epoch some 10 million years age that a land mass approximating to the present day shape of Ireland began to emerge. The present day mountainous tracts were uplifted and their erosion began. The southern coastline was somewhat to the south of the present line.

The Ice Ages

The Ice Age began about 1.75 million years ago when the polar Ice cap expanded and ice sheets centered in various parts of northern Europe expanded and coalesced. The ice cap expanded and contracted several times as climatic conditions fluctuated, the second last expansion being the greatest. In this glaciation an ice sheet thousands of feet thick centered in the north midlands pushed southwards across the country to meet another major ice strain flowing south along the Irish sea, and turning westward along the present coastline. Some of this latter ice sheet pushed its way into the Dungarvan area bringing debris with it from which can be picked out pebels originating in Scotland. The Irish ice sheet was so thick as to leave only the highest points of the Comeragh and Knockmealdown mountains exposed. Thick deposits of glacial till were spread over the area and in some places the glacial drainage channels deposited sands and gravels. At the maximum extent of Glaciation sea levels went up to 100 metres below present levels due to the amount of water blocked up in the ice cap and the coastline was very much further south of the present Waterford coastline. However, the land itself had also subsided due to the enormous weight of ice. After an interglacial period in which temperatures rose to levels possibly even somewhat higher than todays, another Ice Age began about 55,000 years ago. This was less extensive than the previous one and the Midlands ice sheet did not extend any further south than the southern side of the Suir Valley, from Kilsheelan to Clonmel.

However, snow accumulating on the mountains gouged out corries and formed local glaciers which left typical moraine deposits on the landscape. During this period the unglaciated area was initially open Tundra.

The landscape of the central and northern parts of Ireland was completely ice covered only for comparitively short periods, and the landscape was a Tundra similar to that found in Norway today, allowing sparse plant life to grow on mountain tops. At the same time some southern parts of Munster would have been free of the crushing pressure of the heavy ice cap. Here the wooly mammoth, brown bear, artic fox, the Irish giant deer and reindeer would have roamed in a landscape of rich grasslands with some groups of birch or willow trees.

The wooly mammoth had as it's name implies, a hairy coat, in contrast to the two surviving members of the once much larger Elephant group, the African and Indian elephants which have naked skin. Evidence suggests that the wooly mammoth did not appear until the middle of a late interglacial warm stage. Bones of the wooly mammoth and wild horse were discovered at Shandon just outside Dungarvan in 1856.

The caves in the limestone areas of the Blackwater valley provided shelter and fertile soil materials. There were probably rich grasslands with scattered groups of birch and willow where the mammoth and giant deer grazed. There would also have been bear and hyena in the area. There couldn't have been many trees in the landscape as the giant deer would never have survived with its huge antlers. They were about two metres high at the shoulders and over three metres to the tip of their antlers. The antlers were shed annually and grown again each spring.

Ice Age/Warm Spells. 15,000 years ago.

Ireland was then emerging from beneath the glacial ice sheets which had lasted for more than a million years. At this period Ireland and England were joined as land masses to Europe, which allowed animals such as the giant deer to migrate. Pollen records show that the giant deer fed on lush grasses mixed with Alpine plants, sedges, docks and sorrels and the leaves of small willows & juniper. There were few large trees except some birch. Plant seeds were introduced to Ireland by migrating mammals such as hares, lemmings, fox, reindeer and by birds.

The climate became colder and the giant deer migrated to the south east of Ireland where they eventually became extinct.

Warmer Climate

From 10,000 years ago temperatures improved and plants and animals returned to Ireland. Willow, juniper, birch and hazel trees appeared and later pine. The pine birch and elm trees dominated the landscape for more than a millenium. Elm and oak didn't become widespread until later.

Author: Willie Fraher

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