32 GEOLOGY. 



10' in. thick) ; the two divisions are separated by a band of nodules 

 4 to 10 in. thick. This passage-bed contains many species belonging 

 both to the Upper and Lower Gault ; many Lower-Gault forms here 

 become extinct, and many TJpper-Gault forms here first appear. The 

 total number qf species tabulated is 240. Of these, 124 become extinct 

 in the junction-bed, and 39 are continued into the Upper Gault. There 

 are 59 Upper-Gault forms, some of which first appear in the junction- 

 bed, whilst in that bed itself there are 18 species which occur nowhere 

 else. 



The author describes the following new species : — Avellana xmlchella, 

 Natica ohliqua, Nucida Be Rancei. W. T. 



Prestwich, [Prof.] J. On the Geological Conditions affecting the 

 Construction of a Tunnel between England and Prance. Proc. 

 Inst. Civ. Eng. vol. xxxvii. pp. 110-145. (Discussion, pp. 146- 

 170.) Geol. Map and Plate of Sections (plates 8 and 9). 



The author reviews the beds forming the coasts of the Strait of Dover 

 and its neighbourhood, from the London Clay to the Palaeozoic series. 

 The range, depth, thickness, and water-bearing quahties of each are 

 examined. Special attention is given to the Palaeozoic rocks, the author 

 believing that it is through them that a tunnel can best be made. 

 Detailed accounts are given of the various borings in which the 

 Palaeozoic rocks have been reached ; and the author believes that at 

 Folkestone they will occur at from 300 to 400 feet below the sea- 

 level. He thinks the Chalk unsuited for tunnelling, because of the 

 lateral pressure of inland springs, and the probability of meeting 

 with fissures. The Palaeozoic rocks, on the other hand, he believes to 

 be compact and protected by overlying impervious beds. The author 

 concludes by pointing out the light which explorations of the Palaeozoic 

 rocks must throw upon the question of the possible occurrence of Coal 

 Measures beneath the south-east of England. W. T. 



Beade, T. M. Why are the largest Stones found at the East end of 

 the Chesil Bank? Geol. Mag. dec. 2, vol. i. pp. 286, 287. 



The author considers that the insetting tidal current, assisted by the 

 prevailing wind, increases in intensity towards Portland ; here also the 

 wind- waves have most power. By the former action the large pebbles 

 are carried along, and by the latter are finally cast up. " The indi- 

 vidual stones merely follow the law applying to the whole bank, which 

 increases in height and external area as it approaches Portland." W. T. 



. The drift-beds of the North-west of England. Part I. 



Shells of the Lancashire and Cheshire Low-level Boulder-clay and 

 Sands. Quart. Journ. Geol. Soc. vol. xxx. pp. 27-41. 

 A typical section of the Liverpool Drift at the Bootle-Lane Station 

 railway-cutting is described. 



Shells were found at Toxteth Park, Kirkdale Upper and Lower 

 Brickfields, Bootle-Lane Station and Outlet Sewer, Garston, river Dee 

 between Dawpool and West Kirby, Birkenhead Tramway, Gas-works, 

 Linacre, and N.E. of 'Edge-Hill Station, where 37 of the 44 species 



^^' 



