544 REPORT — 1882. 



Per centum 



of clay 



No. II. Grey chalk, yellow band 10-5 



Upper grey chalk 12-0 



Middle 60 



Lower ......... '35-0 



Cast-bed 15-0 



No. 4 of Price IGO 



No. 3 of Trice 40'0 



Chalk marl No. 2 of Price 31-0 



No. I. Chalk marl 1 near bottom ( + sand) . . . 75-0 

 Top of Gault at junction 4o'0 



Bottom of shaft No. II 62-0 



Tunnel end, July 1 ^o-O 



Tunnel end, July 15 42-0 



It is clear from the above table that the clay diminishes as we ascend in the 

 rocks, and that the lower strata of No. II. are the only strata in the series in which 

 no difficulty is to be looked for, from the percolation of water. The three last ana- 

 lyses show "that the amount of clay in the rocks penetrated by the tunnel, in front of 

 the Shakespeare Cliff is very considerable, and that it diminishes as the tunnel rises 

 to the hio-her beds. This change will be a most valuable index to the position of 

 the end of the tunnel in carrying on the work in the rocks under the Channel. 



The water locked up in the pores of the strata penetrated by the tunnel is proved 

 by the analysis of my friend Dr. Angus Smith to be fresh water. 



General Conclusions. 



From the foregoing facts it may be concluded that :— 



1. Tlie lower beds of No. II. (chalk mai-1 2, and the lower part of the grey 

 chalk) are the only strata in the chalk sufficiently impervious to allow of the con- 

 struction of a tunnel in the dry. 



2. That the outcrop of No. II. between Folkestone and the Shakespeare Cliff is 

 the best position for a tunnel, which could strike the lower part of No. II. and 

 remain in it throughout, so as to join the workings of tlie French Channel Tunnel 

 Company wliich are being carried on in the same horizon. 



3. That the faults in the lower part of No. II. do not allow of free percolation 

 of waters, and are not likely to become a serious obstacle to the work. 



4. Tliat the strata above No. II. are so porous, and traversed by open fissures, 

 that they allow of free access to water, both subaiirial and marine, and therefore 

 offer great difficulties in the way of the construction of a submarine tunnel which 

 are not presented by the lower beds of No. II. 



2. On the proposed Channel Tunnels in their Geological Aspects. 

 By C. E. De Range, F.G.S., Assoc. Inst. C.E. 



To those who have not studied the geology of the South-east of England, 

 it may appear somewhat remarkable that the advocates of the scheme of the 

 submarine Continental Railway Company state that the grey chalk will be 

 found to be perfectly dry, while the white chalk will be found to be heavily charged 

 with water, requiring constant pumping. But this apparent anomaly disappears 

 when it is known that the geological horizon called by the East Kent people ' grey 

 chalk,' is the formation so well linown in Sussex and Hants by the name of the 

 rhalk marl, long since described by Dr. Manfell, and, still longer ago, in that much 

 read book ' White's Selborne,' where its great fertility when decomposed into ' white 

 malm,' and its value for hop- and wheat-growing purposes, is discoursed on. 



The chalk marl of East Kent ditfers in no resiJect from the chalk marl of other 

 parts of the country, in being practically waterle.*s, and being the nearly imper- 



