Notable Local Geologists: Charles Lapworth
Charles Lapworth (1842–1920)
Authority on Graptolites and the Lower Palaeozoic
Lapworth is best known for pioneering faunal analysis of Silurian beds in Southern Scotland by means of index fossils, especially graptolites, and also for his proposal that the strata between the Cambrian beds of north Wales and the Silurian beds of South Wales should be assigned to a new geological period: the Ordovician. He is also famous for his fieldwork and interpretation of the geology of the Northwest Highlands, in particular the Moine Thrust.
Lapworth was born in Faringdon, to the west of Oxford, and grew up in the nearby village of Buckland before training as a teacher. In 1864 he took up a teaching post in the Scottish Border region where he investigated the previously little-known fossil fauna of the area. Lapworth recognised the importance of the graptolite fossils in the identification of biozones which could be used to correlate sequences across the area. He was able to show that what was thought to be a thick sequence of Silurian rocks was in fact a much thinner series of strata repeated as a result of faulting and folding. His work resulted in the Geological Survey having to re-map and re-interpret the entire area. His researches were published in 1899, in the ‘Memoir on the Geology of the Southern Uplands of Scotland’.
"Darwin was a biological evolutionist, because he was first a uniformitarian geologist. Biology is pre-eminent to-day among the natural sciences, because its younger sister, Geology, gave it the means."
Charles Lapworth (1903)
Lapworth decided to remain in Scotland and in 1875 he became an assistant at Madras College in St Andrews, Fife. His knowledge of the distribution of graptolites and associated trilobites and shelly fossils, enabled him to correlate the Scottish rocks with sequences of similar age in England and Wales. Lapworth became the foremost authority on graptolites and his numerous scientific papers culminated in the ‘Monograph of British Graptolites’ (1901–1918) written under his editorship by the Misses Elles and Wood.
His understanding of the fossil fauna of the Lower Palaeozoic led to his resolving the great Cambrian – Silurian controversy. The boundary between Adam Sedgwick's Cambrian System and Roderick Murchison's Silurian System had been in dispute for many years. Lapworth resolved the issue by demonstrating three distinct fauna. He used these to divide the Lower Palaeozoic into three rather than two stratigraphic units – the Cambrian System (oldest), a new system that he named the Ordovician, and the Silurian System (youngest). The Ordovician, named after a Roman-British tribe that inhabited northwest Wales, incorporated Sedgwick’s Upper Cambrian and Murchison’s Lower Silurian. His work was published in 1879 as ‘On the tripartite classification of the Lower Palaeozoic rocks’.
By the late 1870s Lapworth had gained a significant academic reputation and in 1881 he was appointed as the first Professor of Mineralogy and Geology at Mason College, the forerunner of the University of Birmingham. His title was subsequently changed to Professor of Physiography and Geology. For his first research project at Birmingham, Lapworth chose to re-examine the geological structure of the Northwest Highlands of Scotland which had been investigated by Murchison in the 1850s and 1860s.
Murchison had believed that the Moine schists, previously supposed to be ‘Primitive’, were no older than his recently created Silurian period, because limestone and quartzite containing ‘Lower Silurian’ (Cambrian) fossils lay beneath them. From 1858 Archibald Geikie aided Murchison in his mapping of Scotland. They traced out the contact between the Cambrian strata and the Moine Supergroup, believing it to be stratigraphic despite having recognised that the Moine was metamorphosed but the underlying strata were not. James Nicol, Professor of Geology at Aberdeen University, was amongst the first to dispute this interpretation. He believed that the Moine was faulted against the Cambrian and ’forced over the quartzites’, even suggesting that the Moine might represent rocks that underlay the Cambrian. He said the fault was an important structural feature which could be traced from Durness to Skye and showed this on his 1858 Geological Map of Scotland. Murchison and Geikie could not accept Nicol’s theory and there began the acrimonious debate known as the ‘Highlands Controversy’. Following Nicol’s death in 1879 Lapworth took up the cause. He had already been scorned as an amateur by Geikie, from 1867 the Director of the Scottish Geological Survey, for his theories on the Southern Uplands.
"Nothing perhaps has so retarded the reception of the higher conclusions of Geology among men in general, as ... [the] instinctive parsimony of the human mind in matters where time is concerned."
Charles Lapworth (1903)
By the end of 1881 Charles Calloway, a museum curator, had confirmed Nicol’s findings and found a whole series of faults. Lapworth, working in the Loch Eriboll area near Durness, found that both the quartzites and the gneisses on which they were deposited were tectonically repeated. In several publications in 1883 Lapworth described how sheets of Moine schists were transported westwards across the basement of Lewisian, Torridonian and Cambrian rocks, and he indicated similarities with structures in the Alps. He also described how strata were smeared out by the over-riding thrust sheet, forming mylonites. Geikie sent his geologists Ben Peach and John Horne to the area and when they supported Lapworth’s interpretation, Geikie did a volte-face, wrote an article for ‘Nature’ describing Peach and Horne’s findings and introducing the term ‘thrust’. Little credit was given to Lapworth or Calloway. Peach and Horne spent the next 15 years mapping the Northwest Highlands during which they corresponded with Lapworth. They confirmed that there did indeed exist a major fault, now known as the Moine Thrust, between the Northern Highlands, the rolling hills of the Moine Supergroup to the east, and the rugged mountains of the Archaean and Proterozoic Hebridean Terrane unconformably overlain by Cambrian strata to the west. Their work was finally published in 1907.
Whilst in Birmingham, Lapworth studied the rocks of the Midlands and Welsh Borderland and took groups of students, amateur and professional geologists on field excursions. He mapped the Lower and Middle Cambrian rocks in the Harlech district, proved the existence of Precambrian rocks at Nuneaton, and made important discoveries of Lower Cambrian fossils in Shropshire. He also made significant contributions to the Royal Commission on Coal in connection with the Midlands coalfields.
‘Lake Lapworth’ in Shropshire was so named by Leonard Wills following Lapworth’s suggestion of its existence in 1898. It was thought that about 13 500 years ago, when ice from Wales and the north blocked the outlet of the River Severn near modern Chester, the river backed up and formed a lake – Lake Lapworth – until it overflowed southwards and cut the Ironbridge Gorge. The theory was generally accepted until the 1980s. In the 1970s a buried trench was found below the course of the Severn, cut deep into glacial deposits or bedrock. It appears that water flowed through this channel under pressure, under an ice sheet or glacier, and rose up the ice front to cut the gorge. The evidence now suggests that ‘Lake Lapworth’ did not exist, although there may have been smaller glacial lakes at the margins of the ice.
The Lapworth Museum on the campus of the University of Birmingham houses an extensive collection of fossils, minerals anand, dating back to 1880, is one of the oldest specialist geological museums in the Britain.
A gallery of
Hover cursor over the image for a description.
Upper section of map by Lapworth of the area around Durness and Loch Eriboll in Sutherland (Lapworth Archive, Lapworth Museum, University of Birmingham).
Lower section of map by Lapworth of the area around Durness and Loch Eriboll in Sutherland (Lapworth Archive, Lapworth Museum, University of Birmingham).
Cross-section by Lapworth of the area around Durness and Loch Eriboll in Sutherland (Lapworth Archive, Lapworth Museum, University of Birmingham).
The Moine Thrust at Knockan Crag. Dark layered rock in the upper part of the photograph is mylonite formed from Moine Schists. The Moine Thrust lies between these rocks and the white Durness limestone in the centre of the photo. Below can be seen grey Durness limestone (photo: Dave Waters/Simon Lamb, Rocks of NW Scotland, www.earth.ox.ac.uk).
Shale beds at Dob's Linn, near Birkhill, Southern Uplands, where Lapworth studied the graptolite fauna in the transition from the Ordovician to the Silurian strata. Photo Jim Barton (Creative Commons).