Lonsdale, William
Lonsdale, William
(b. Bath, England, 9 September 1794;d. Bristol, England, 11 November 1871)
geology.
Lonsdale was the younger son of William Lonsdale of Bath. He obtained an army commission in 1812, served in the Peninsular War, and was present at the battle of Waterloo. When peace was restored in 1815, he retired from the army on half-pay and settled near Bath, He never married. Lonsdale’s interests inclined toward natural history, and in 1826 he was appointed a curator at the Bath Museum. He was elected to the Geological Society of London in 1829, and soon afterward was appointed curator and librarian to the society. Lonsdale worked hard at cataloging the society’s rapidly growing collections; in 1838 his post was redefined, and as assistant secretary and librarian he undertook an increasing administrative and editorial burden. In 1842, poor health forced him to resign, and he retired to southwest England for the rest of his life. In 1846 he was given the society’s highest award, the Wollaston Medal, for his work on fossil corals.
Shortly before his election to the Geological Society, Lonsdale contributed an excellent, although conventional, account of the stratigraphy and paleontology of the area around Bath. Once he was in the society’s employment, he had little time for writing. His work, however, gave him an unrivaled knowledge of British fossils, which led to his most important contribution to geology.
In the late 1830’s the geology of Devonshire became fiercely controversial because of the assertion by Roderick Murchison that the government’s official geological surveyor, Henry De la Beche, had misinterpreted the entire sequence of strata and had overlooked the presence of a large area of strata of Coal Measure (that is, late Carboniferous) age. Most geologists agreed, however, that the older strata of Devonshire were pre-Silurian because of their litho-logical character. In 1837, however, it was asserted instead that the fossils in these rocks indicated a Mountain Limestone (that is, an early Carboniferous) date. Lonsdale immediately suggested, on the basis of his own studies of the fossil corals, that the strata were neither Carboniferous nor Silurian, but inter-mediate in age, since some fossil species were known from the Silurian, some from the Carboniferous, and some from neither. This implied that the Devon rocks were the lateral equivalents of the Old Red Sandstone, despite their totally different lithology. This seemed so improbable that Lonsdale’s suggestion was virtually forgotten until 1839, when it was adopted by Murchison and Adam Sedgwick and became the basis of their Devonian system. The validity of Lonsdale’s hypothesis was then quickly confirmed by the recognition of the same fossil fauna in the expected position in clearer sequences of strata elsewhere in Europe and in North America.
The Devonian controversy involved much more than a technical or local problem. The argument turned on the reliability of fossils for the estimation of the relative geological age of strata in the absence of clear evidence from superposition and in the face of clear contrary evidence from lithology. Even more fundamentally, this methodological argument depended on conceptions of biological history. Lonsdale’s hypothesis was based on his perception of the intermediate character of the Devonian corals; it was valid only if the fauna had been transformed in the course of time by the gradual production of new species and extinction of old species and in a roughly synchronous manner over a very wide area, with anomalies in only exceptional circumstances (as, for example, the unusual Old Red Sandstone environment). The vindication of Lonsdale’s hypothesis was therefore taken as confirming strongly the validity of correlating strata by means of fossils, even on an intercontinental scale. It was thus highly influential indirectly in the development of stratigraphical geology.
BIBLIOGRAPHY
Lonsdale’s principal scientific publications were “On the Oolitic District of Bath,” in Transactions of the Geological Society of London, 2nd ser., 3, pt. 2 (1832), 241–276; and “Notes on the Age of the Limestones of South Devonshire,” ibid.,5, pt. 3 (1840), 721–738. The history of the Devonian problem is summarized in M. J. S. Rudwick, “The Devonian System: A Study in Scientific Controversy,” in Actes du XIIe Congrés international d’Histoire des Sciences,7 (Paris, 1971), 39–43. Lonsdale’s work for the Geological Society is referred to in Horace B. Woodward, The History of the Geological Society of London (London, 1907).
M. J. S. Rudwick