183 FEATURE © John Wiley & Sons Ltd, The Geologists’ Association & The Geological Society of London, Geology Today, Vol. 30, No. 5, September–October 2014 Feature Geology and the war on the Western Front, 1914–1918 Peter Doyle Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK geologytoday@btinternet. com The First World War started a hundred years ago this year. On 4 August 2014 the United Kingdom marked the anniversary of involvement in this war with a remembrance event at Mons, and over the next four years there will be new museums and exhibitions, services and events, conferences and colloquia world-wide. The aim of this collective recognition of a major event in world history is to pick over the impact and effects, innovations and consequences of a war that claimed the lives of at least 16 million people and left the world with geopolitical issues that still reverberate today. One of its notable innovations was the use of geology in warfare. As is well known, compared with the open war fought against the Russians on the eastern front, the war in the west very quickly became positional, with opposing trench lines locked into a position that would dictate the war’s approach. And with trench warfare, came the need to understand the geology of the land over which the men were fighting. The First World War was fought principally on two fronts in Europe—described as the Western and East- ern fronts respectively—from August 1914 to No- vember 1918. Not confined to Europe, the war spread world-wide, with lesser known land campaigns in the Middle East, Asia and Africa, and with a naval war that saw action from South America to the North Sea. In Europe, the ‘Triple Entente’ (France, Britain and Russia), faced the Central Powers (principally Germa- ny and Austria-Hungary), but other countries took their place in the developing battlefields, with Serbia and Belgium embroiled from the outset. The origins and early development of the war are too complex to enter into here, but with Germany committed to the war, the Schlieffen Plan of 1904 was enacted, a plan which dictated an assault on France through neutral Belgium, in order to knock its enemies of 1870–71 out of the war—before taking on the might of Russia. The plan predicted the advance of a great arc of German armies through northern France and Belgium. Its aim was to engulf and surround Paris, thereby knocking its principal enemy out of the war. The invasion of neutral Belgium brought Britain into the war, and the British Expeditionary Force took its position in the line at the town of Mons in late August 1914. The weight of the German invasion was such that the French and British troops fell back to take up a po- sition along the line of the River Marne before Paris, and in the battle that ensued from 5–12 September, the German advance was stopped in its tracks. With the Schlieffen plan in disarray, from 13 September to 19 October the Allied and German armies attempted to outflank each other in what has become known as the ‘Race to the Sea’. By November 1914, both armies in the west had ground to a halt in parallel lines that stretched from the North Sea to the Swiss Frontier—a situation that was to remain in place until the lines were broken in 1918, leading to the resumption of open warfare (Fig. 1). Throughout history, the most effective military commanders have been those who have understood topography and the nature of terrain, with records at least back to some 512 bc recorded in the Chinese text attributed to Sun Tzu, in the Art of War. Of its 13 chapters, at least seven of them refer explicitly to the use of terrain in battle and manoeuvre, the