Reading between the Giant’s Causeway basalts

by Tas Walker

Article from:
September 2009

Photo by Angus Kennedy

the Giant's Causeway

One striking feature of the cliffs at Giant’s Causeway, Northern Ireland, is an orange bed that forms a prominent band in the sheer basalt face. This bed creates a natural bench and the cliff path follows it around the bays. It is 10–12 metres (30–40 ft) thick and composed of soft, friable, red and brown material. Technically it’s called the Interbasaltic Bed—i.e. the bed between the basalts.1,2

The standard story is that the Inter-basaltic Bed is a thick soil that formed by weathering over an unimaginably long time. For example, the website of the Giant’s Causeway Visitors’ Centre says of that layer, “During 2 million years of warm, wet climate the lower basalt weathered to form a deep red rock called ‘Laterite’.”3 On the face of it, this seems to be an argument for long ages and to contradict the biblical timescale.

However, such soil is unlike any forming in the United Kingdom today, so geologists propose that in the past the climate was warm and wet like tropical Africa. They say the exposed top of the Lower Basalt weathered into a thick soil that supported lush vegetation for perhaps two million years. Then the next lava flow erupted and covered the landscape.4

However, there are problems with this idea:

So although on first glance the bed looks like a soil, on closer examination it is clear that it was not formed by slow-and-gradual weathering over a long period of time. Rather, the thick bed was buried quickly by the later lava flow, and chemically altered by the heat that remained after the lava had been quenched in the retreating floodwaters. Interpreting the Interbasaltic Bed within a biblical Flood framework makes better sense than long-age explanations.

[Update 22 August 2011]. As shown in the diagram above, the basalt flows comprising Giant's Causeway erupted during the Abative phase (or Sheet-flow phase) of the global Flood, as the floodwaters were receding from the continents. The thick bed of sediment, which also contained vegetation, was rapidly deposited by the receding waters on top of one of the lava flows and covered quickly by the next basaltic flow. Heat and fluids from the basalt combined with the abundant water in the sediment chemically altered the bed and coalified the vegetation within it. The presence of abundant water prevented the sedimentary bed from being baked by the subsequent lava flow.

Related articles

Wilson, H.E., Regional Geology of Northern Ireland, Geological Survey of Northern Ireland, Belfast, pp. 63–64, plate 9B, 1986.
Lyle, P., A Geological Excursion Guide to The Causeway Coast, W&G Baird, Antrim, Northern Ireland, pp. 24–25, 1998.
Giant’s Causeway Visitors’ Centre, Geology, <>, 2008.
Explore The Giant’s Causeway, The National Trust, Saintfield, Northern Ireland, p. 6, 2002.
The lignite deposits do not represent a soil horizon. In soil, the decomposed organic material is finely dispersed.
Readers’ comments
Pamela S., South Africa, 17 January 2011
Thank you for putting Giants Causeway into perspective. I have been once before but look forward to new knowledge when I go again in May 2011. Though the two giants story is also quite a tale to tell.
Graeme W., Canada, 18 January 2011
I read this article on the band of soil above the Basalt of the Giants Causeway and I was left at the end of the article looking for page two. The article could be improved by clearly giving the flood conditions that would have explained it. You have told me the standard story but now you should clearly present the Biblical flood view explaining how this band may have formed.
John B., United States, 18 January 2011
I was impressed with the article which should help debunk the Lie that is the Geologic Column. That did not come into being until the 1830s by another pseudoscientist, in the same vein as pseudoscientist Darwin who did not have a degree in biology or any real scientific training. I am saddened that the U.S. Geologic survey refuses to re-evaluate away from the false Geologic Column instead of looking more closely at the real rather than the false and misleading geologic column.