Well last week I brought you and myself on a journey back to the very beginnings of Ireland and Waterford in particular, geologically speaking and all this courtesy of a wonderful book by Declan McGrath, the Wildlife of Waterford City.
Now for one more instalment but this time we are dealing with more recent geological events – a mere 1.5 million years covering the Quaternary Period. During this period the land hereabouts was covered and scoured by vast ice sheets, especially from the midlands and also from the Irish Sea basin. There were many ice ages during this period which deposited layers of boulder clay, up to 20 metres deep in places, over the area surrounding Waterford City.
When the ice sheets melted, the land beneath it rose but so did the sea level, partly as a result of huge amounts of meltwater arising, which cut deep channels through the bedrock over an extensive flood plain generally in an easterly direction before veering southwards to the sea at Waterford Harbour. Much of the river plain has been embanked so that the river is now more defined and more stable, though it, the Suir, remains a dominant feature in the City.
The Suir and the surrounding flood plain carried most of the melt waters, though other smaller flood plains and rivers joined the main channel, of which only the St. John’s River remains. In more recent centuries the flows of the smaller rivers have been drastically changed and even the course of the St. John’s River has been altered and its extensive flood plain removed (I wonder does the Tramore Road flooding problems date back to that era).
However both of the rivers continue to carry a sediment load, albeit very much reduced in comparison to the dramatic upheavals of the early Quaternay. This sediment load is being continuously deposited along the banks of the Suir, which limits access to and limits recreational usage of the Suir along most of its tidal length. The small saltmarsh area along the Suir within city limits hold deep loads of fluviatile mud (depths of at least 4 metres have been reached near the Island ferry) and development in low-lying areas is only possible once the ground has been piled. So as you can see that our geology can have, indeed, has had a crucial bearing on development in Waterford.
Well, here’s a quick summary / overview of some of the things we have learned about the foundation (literally) of Waterford and hereabouts. The Waterford area has been covered by deep oceans and later by shallow seas, regularly subject to volcanic eruption ( remember Waterford has an acclaimed geo-park and note the information displays at Kilfarassey), and then washed by torrential rivers carrying massive amounts of sediments and finally, and more recently, buried under massive glaciers, which scoured and eroded the land. However little evidence of these upheavals remain and is usually well hidden under the soil layer though recent road excavations give some clues to the local geology (for example, Sallypark and more clearly at the flyover bridge at Lacken on the Outer Ring Road and at the Waterford & Suir Valley Railway terminus at Bilberry).
Many of the underlying rocks of the City are slaty mudstones and they are too soft to be used for roofing. Some Lower Palaeozoic rocks were used for local building purposes. These are best seen in old walls and even in Reginald’s Tower! But they are no longer in use as dimension stone in buildings nowadays as they break into unsuitable irregular blocks. The Roadstone lorries are a familiar sight in these parts and many of these carry crushed limestone, aggregates and concrete products from the Kilmacow Quarry at Granny formed during the Carboniferous Period (355-290 million years ago).
Brick Factory at Bilberry
Quarry Road in Gracedieu is so named from the small quarries nearby and is also known as the Red Road from the red sandstone of the area (and used in the stone walls there). Bilberry sustained an active quarry up to the late 1950s, from where fill and surface material was extracted by Waterford Corporation, as it then was. A brick factory also operated from here in 1898, using crushed stone from the same quarry. More recently, excavation works associated with the reinstatement of the tourist railway at Bilberry has revealed the very friable Old Red Sandstone rocks of this rapidly developing area.
The principals soils to be found in Waterford City are mainly acid brown earths derived from sandstone or rhyolite till with some limestone glacial till and associated soils including gleys, podzols and grey brown and brown podzolics (Now that’s a mouthful, alright). Soil depths vary from one to three metres and the soils are usually well drained except the gleys, which have a high clay and silt content. Gley soils are found mainly around the flood plain of the St. John’s River at Kilbarry (an area by the way is destined to have a great ecological future!). There are few rock outcrops, apart from the Black Rock at Kilbarry and small projections on the Dunmore Road near Ernst & Young. Knew the DMR would get into the story somewhere!
Well hopefully, if you stayed with me and D. McG, you will have learned some of Waterford’s underlying story – forces that shaped they way we are fundamentally. Another we will look important habitats of Waterford City with a special attention to the Island and the King’s Channel Salt Marsh which I found fascinating – an area just a stone’s throw from us here.