History of Geology in Wales

Posted by John Henry on

Best wishes for the New Year to all website visitors and customers of geolmaps.com. In this article I am featuring maps, memoirs and books concerning the geology of Wales and the rich history there of the development of geology. That Wales gives the names of three of the systems of the stratigraphical chart – Silurian, Ordovician and Cambrian and, until recently Precambrian - attests to the early exploration and conceptual thinking that occurred here. The Silures and Ordovices were early Celtic tribes encountered in Wales by the Romans. The Cambrian Mountains form the uplands of Mid-Wales.


Arthur Aikin (1773-1854) described the lithology and mineralogy that he encountered in his book, Journal of a Tour Through North Wales and Part of Shropshire, published in 1797. Unfortunately, he did not plot his tour or observations on a map, although he considered that lithology could be interpreted from the form of the mountain ridges. Aikin was an assayer and mineralogist who was a founder member of the Geological Society and its secretary from 1812 to 1817.


The earliest published geological map of a part of Wales was Roderick I Murchison’s (1791-1871) The Silurian Region, 1839. In it he classified the area of sedimentary sediments of Mid and South Wales as a widely recognisable system based on fossil evidence. The original map accompanying his great two volume opus, The Silurian System, was usually dissected, mounted on linen and folded in its own case. Today it is difficult to acquire a complete set of texts and the map, which is rarer. Recently acquired for sale is an undissected original issue of the map in three parts.

As Murchison defined ‘his’ Silurian System, it encroached on the Cambrian system that his colleague and, subsequently, rival Adam Sedgwick (1785-1873) was working on in North Wales. Their dispute is recorded in Jim Secord’s book, Controversy in Victorian Geology: The Cambrian-Silurian Dispute. Murchison summarised his early work in his book Siluria, whereas Sedgwick only published in articles such as ‘On the Older Palaeozoic (protozoic) rocks of North Wales’
Murchison went on to succeed De la Beche in 1855 as head of the Geological Survey; he encouraged further field work and detailed mapping. This was accomplished by the continuance of the one inch survey mapping and pulled together in volume III of the Memoirs of the Geological Survey by Andrew Ramsay (1814-1891) in 1866. A much expanded second edition was published in 1881 when Ramsay himself was Director of the Geological Survey.

Ramsay’s and Murchison’s works and the first edition one inch mapping by the Geological Survey  were the accepted status quo until the early 20th century when larger scale mapping of small areas by several individuals heralded a revision in detail. Much of this new work was published in the Quarterly Journal of the Geological Society.

Queries about any of the above geological maps and books, or any others, are welcome, please enquire. Visitors are welcome at our London address, by appointment.

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