750 REPORT—1899. 
9. Investigation of the Underground Waters of Craven. The Sowrces of 
the Aire. By Peroy F. Kenpatt, /.G.S. 
10. Lhe Recent Eruption of Hina. By Professor GIOVANNI PLATANIA. 
The eruptions of Etna from the central crater are less frequent than in the 
case of Vesuvius. The last great eruption was in 1892, when 2,470 million cubic 
feet of lava was poured forth from a crater on the southern flank. On July 19 
a Plinian eruption occurred in the central crater, during which a great number 
of ejected blocks of old lava were scattered round the crater to a distance of 
over 4,000 feet. Some of the blocks damaged the roof of the Observatory. It 
is suggested that this Plinian eruption is a symptom of an impending lava erup- 
tion, which will produce a rift in continuation of that of 1892 in the Valle del 
Bove. 
TUESDAY, SEPTEMBER 19, 
The following Papers and Reports were read :— 
1. The Geological Conditions of a Tunnel under the Straits of Dover. 
By Professor W. Boyp Dawkins, IA., F_Z.S. 
In 1882 the physical structure of the cliffs on the English and French sides of 
the Straits was brought by the author before the British Association. Since that 
time the question of a tunnel has been relegated to a future more or less remote, 
while many new facts have been ascertained. It is not, therefore, inopportune to 
recur to the subject, which has a special interest for the place of our present 
meeting. 
The rocks exposed in the cliffs between Folkestone and St. Margaret’s, and 
measured for the purposes of the proposed tunnel, are as follows, in descending 
order :— 
Thickness. 
English Feet. 
[ VI. St. Margaret’s Chalk. . . ’ . - 280 
Upper. | _V. Nodular Chalk with flints ‘ 3 ‘ . « 100 
| IV. Chalk with few flints . : : : 3 - 100 
Middle. III. Lower White Chalk with Nodular layers without 
. 145 
flints . : - ‘ S . : : 
Taaer { TI. Grey Chalk and Chalk Marl No. II. of Price . - 225 
wer. ) J, Glauconitic Marl, No.I.of Price . . . «6 38 
Gault. 
The Gault, a stiff blue impervious clay, forms a low line of cliffs on the west 
side of Eastwear Bay, and disappears beneath low-water mark, opposite the 
western end of the Abbotscliffe. It occurs in St. Margaret’s Bay in Sir John 
Hawkshaw’s boring at a depth of 536 feet below O.D. 
_ The Glauconitic Marl, No. I.,a clayey calcareous deposit, generally impervious, 
but sometimes so full of grains of glauconite and sand as to be pervious, overlies the 
Gault and passes into the chalk marl, underlying the Lower Grey Chalk, No. IT. 
This sets in in the cliff traversed by the Folkestone Tunnel at 360 feet above O.D., 
and descends to Ordnance datum, a little to the east of Shakespeare’s Cliff. It con- 
stitutes the base of the cliff from A bbotscliffe as far as that point. 
SS ee ay 
a i i 
