Early Ideas About Glaciation in the English Lake District: The Problem of Making Sense of Glaciation in a Glaciated Region
An account is given of the work on glacial phenomena in the English Lake District from the time of Adam Sedgwick until the mid-twentieth century, with emphasis on the nineteenth century. In the early years, the following theories were envisaged: 'diluvialism'; the theory of 'waves of translation'; the theory of 'ice rafting'; the 'glacial-submergence' hypothesis ('marinism'); and the 'land-ice' theory. While it was quite easy (after Agassiz) to recognize ice action and the former existence of glaciers, it was difficult to work out a persuasive sequence of events that would account satisfactorily for the great variety and quantity of evidence available, considering land-forms, and the distribution of moraines, tills, gravels, and glacial erratics. When the first systematic geological survey was being undertaken in the Lake District (1866-88) both local amateurs and the surveyors favoured the glacial-submergence theory, but there were problems about explaining the distribution of glacial erratics, and controversy developed as to whether this distribution was best explained in terms of floating icebergs or landice. The problem was difficult in that there was uncertainty as to how many glaciations there had been, though the preferred number was two, following the early observations in Wales by Andrew Ramsay, in Lancashire by Edward Hull and others, and by some Continental geologists, of two different tills, and one intermediate water-deposited unit. These seemed to have equivalents in the Lake District. However, the Scottish surveyors, under the influence of their theorist colleague, James Croll, with his astronomical explanation of ice ages, favoured multiple glaciations. Croll himself sought to apply the land-ice theory to explain the distribution of glacial erratics in the regions round the Lake District. James Geikie read widely in the Continental literature, and thought that the theory of several glaciations, developed by Albrecht Penck in the 1880s, on the basis of observations of the valleys and rivers terraces running north from the Alps, fitted well with Croll's theory. Thus the idea of a sequence of glaciations was applied to Britain with some success, partly as a result of Geikie's advocacy. But the evidence of such a sequence in the Lake District itself was by no means clear, and it was not developed for the region until the work of Frederick Trotter and Sidney Hollingworth (1932). In the meantime, much geomorphological work on the form and formation of lakes and tarns had been done by the chief aficionado of Lakeland geology, Cambridge professor, John Marr. But he thought there might have been only one major glaciation. The paradox is that, for England, the glacial sequence has had to be worked out more by examination of deposits in the flatter southern regions, as much as in the mountains where the glaciers were formed and most active. In the Lakeland mountains, as in other parts of the world, the last glaciation has tended to remove or obscure the products of earlier glaciations.