The Area Studied During the last four years of war the British military base in France has included practically all the seaports from Calais to Le Havre, and the roughly triangular area between this coast and the part of the front held by them was traversed by their lines of communication and occupied by base depots, training camps, hospitals, rest camps, railway construction troops, and other auxiliary forces to an extent which involved a very large temporary increase in its normal population. It is nearly all underlain by the chalk formation, with the exception of Jurassic areas around Boulogne and to the southwest of Amiens, a Tertiary area which covers the Belgian part of the front and extends nearly as far west as Calais, and another between the Somme and Canche rivers to the north of Amiens. To the south of the line of highlands which runs southeastwardly from Cape Gris Nez the . . .
- Received 15 January 1919.
- © 1919 Geological Society of America