On one hand, this is the story of how many of the older geological periods of the Phanerozoic: the Cambrian, Ordovician, Silurian, Devonian and Permian, were first recognised in the 19th century and got their names. More immediately and interestingly, it is also a memoir of three pioneering British geologists: Sedgwick, Murchison and Lapworth, and their part in two of the most notorious geological controversies in the development of British geological knowledge. These were the stratigraphical subdivision of the Lower Palaeozoic in Britain (encompassing the mudrocks, sandstones and limestones of Wales, the Lake District and the Southern Uplands of Scotland) and, consequently, worldwide, and the stratigraphical relationships of the rocks found in northern Scotland, especially those of the north-west Highlands. The book also explains something of the early work of the British Geological Survey (then known as the Geological Survey of Great Britain), including some early examples of fraught relationships between senior officers of the GSGB/BGS (Murchison was the second director of the survey) and academic geologists.
Carefully and extensively researched (including visits to some of the key localities), and clearly and thoughtfully written, this book is a very readable account of three very disparate scientific personalities. Davidson is not a formally-trained geologist but he knows the subject well enough to communicate the concepts clearly. The level of technical detail seems about right – enough to explain the problems that these geologists were facing (and, eventually, solving) but not, I think, to discourage the non-geologist reader. There are a very few stumbles over lithological nomenclature: on p. 40 and p. 237, ‘shale’ is a fissile mudstone, not a ‘fine-grained mixture of mud and limestone’. The short glossary is not entirely reliable: gneiss is generally coarser-grained than schist, I would say, and anyway texture is a more important distinguishing feature of these rock types than is grain size. But these quibbles do not affect the substance of the narrative.
The book describes, through the career of Murchison, how social standing, networking and wealth can combine with ambition, self-belief and self-promotion to lead to preferment. Arguably, Murchison was the least able scientist of these three geologists, but was someone who used rapid survey and ‘broad-brush observation’, combined with well-developed organisational and communication skills, to, mostly, good effect. History seems to show that he was not always the most diligent observer, and in some cases, apparently allowed his preconceptions to over-influence his interpretation.
The brilliant Sedgwick was hindered as a research scientist by his need to earn a living, as a university professor and a cleric. Coupled with an apparent tendency to be distracted (and in later life, bouts of ill-health), he didn’t share Murchison’s facility for writing – or self-promotion. But history has been kinder to his scientific interpretations.
Lapworth came on the scene somewhat later, bringing his meticulous research into graptolite faunas in the Southern Uplands to fruition only after Murchison and Sedgwick had died. He was, perhaps, the most able of the three, a careful observer, coming to the rocks with, it seems, a very open mind, capable of seeing the big picture — and of communicating it. Also, Davidson tells us, he was a capable teacher, and who was able to continue his research and writing while continuing with his professorial duties.
The book’s title, ‘The Greywacke’, alludes to the use of this term in the early 19th century, as a ‘catch-all’ to describe the Lower Palaeozoic mudrock-sandstone terrains of Britain. There is a useful final chapter, serving as a postscript, on the formation of ‘greywacke’, as the term is used in the sense of the more modern term of ‘wacke’, to denote a very poorly sorted muddy sandstone — and the origin of the concept of turbidity currents some 80 years after Sedgwick and Murchison died. They apparently had no idea of how major elements of the sequences they mapped were formed.
As a one-time professional geologist, I commend this book to anyone who is interested in the history of geoscience. There are other books that have described the same geological controversies and their protagonists, but I doubt that any are as readable as this.