The Channel Tunnel / reports by British and French engineers ; papers on national defence by Sir William Butler, Sir Alfred E. Turner and Sir Charles Campbell ; edited by W.T. Perkins.

Date:
1907
Catalogue details

Licence: In copyright

Credit: The Channel Tunnel / reports by British and French engineers ; papers on national defence by Sir William Butler, Sir Alfred E. Turner and Sir Charles Campbell ; edited by W.T. Perkins. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    7/80
    RELIEF-MODEL. The model in relief, now exhibited for the first time, has been prepared by direction of the French Submarine Tunnel Company, to show the proposed arrangements for the Channel Tunnel entrance and exit, together with the geological configuration of the stratum through which the Submarine Railway will pass, if sanction be given to the Bill before Parliament. The scale is 1/20,000 horizontal, and 1/1,000 vertical. Divided horizontally into several parts, the model shows successively the super-position of the different strata constituting the bed of the Straits of Dover, as well as the formation of the adjacent cliffs on either side of the Channel. Thus, in the lower part, are seen the Jurassic, Wealden, Gault, and the Cenomanian (1), through which the two parallel tunnels, each 18 feet diameter, will be driven ; while in the upper part are the Turonian (2) and the Senonian (3). Vertically, the model is made in two independent parts, so as to exhibit a sectional view of the different strata (variously coloured to facilitate examination), and especially the dip of the strata towards the north. These various strata have been ascertained by means of over 7,000 soundings, which brought to the surface more than 3,000 samples, all geologically accurate. The soundings took over two years to be performed from a boat right through the Channel. This important work occupied more than two years, and involved the employment of a vessel chartered for the purpose by the French Submarine Tunnel Company ; and thus it became possible to complete an extensive and careful survey. The undulations of the sea bottom are shown on the upper part of the model, so as to give an idea of the depth of the sea at various points of the Straits. This arrangement enables the course of the strata enumerated to be indicated as clearly as if it were illustrated on a map ; and it will be observed that the bed of the Channel between Dover and Sangatte, on the French coast, takes the form of a letter “ M ” very much stretched out. (1) Upper Greensand. (2) Chalk marls and Chloritic marls. (3) Upper (white) Chalk (with flints) and Lower Chalk (without flints).