SCIENTIFIC SUMMARY. 
317 
shaped masses at various points, especially to the west of the British Isles, 
south of Cork in the Bristol Channel, between Land’s End and the Sor- 
lingues Islands, and also in the Channel. In the eastern part of the Channel 
gravel occupies a large surface, and seems to unite the Greensand of Upper 
Normandy to that of England. In the Bristol Channel and to the South 
of Ireland, M. Delesse suggests that the origin of the gravel is probably a 
submarine outcrop of Old Bed Sandstone ; south of Exmouth and of Star 
Point it may be referred to the prolongation under the sea of the arenaceous 
Triassic beds. The distribution of mud is next investigated. The patches 
of mud-bottom in the Channel are due doubtless to the Palaeozoic schists, 
the Triassic clays, the Liassic marls, and the Eocene clays. They can be 
traced from Dover to the Lizard. 
The Sub-Wealden Exploration in Sussex . — The boring to prove the 
Palaeozoic rocks of Sussex, which was commenced in 1872, is — says the 
u Geological Magazine/’ June, 1874 — now being carried on with great 
vigour. The adoption of the Diamond method of boring has proved a great 
success. Mr. Henry Willet, in his Sixth Quarterly Report, dated March 
28th, states that a total depth of 671 feet has been reached. The drill, 
called the " Crown,” is a ring of soft steel 3^ inches in diameter, and has 
15 diamonds set in it round its lower edge. It revolves at a speed varying 
from 150 turns a minute in soft strata, to 300 in hard rock. Water is 
pumped down the centre, and rising at the sides, conveys the debris in sus- 
pension to the surface. The diamonds are not brilliant, and have no 
cleavage planes; they come from Brazil, and are called u Carbonado.” The 
cores brought up are sometimes six or seven feet long in one piece, and form 
a beautiful section of all the strata passed through. The fact that delicate 
shells are found lying at right angles to the axis of the bore, is an indisput- 
able proof that the beds are horizontal. 
The following strata have been penetrated : — 
feet 
in. 
feet 
in. 
Shales 
. 17 
0 
Dark gypsum, impure 
13 
0 
Blue limestone . 
2 
0 
Blue shale . 
3 
0 
Shale . 
’. 1 5 
0 
Gypsum in nodules and 
Blue limestone . 
. 2 
0 
veins .... 
13 
3 
Shale . 
. 4 
0 
Gypsum marl 
8 
0 
Limestone . 
. 1 
0 
Black sulphurous marl 
1 
0 
Shale . 
. 4 
0 
Greenish sand, with nodules 
Limestone . 
. 3 
0 
of chert .... 
21 
0 
Shale . 
. 4 
0 
Sandy shale, with nodules 
Limestone , 
. 4 
0 
of chert .... 
38 
0 
Blue shale . 
. 16 
0 
Carbonate of lime veins 
2 
0 
Grey shale . 
. 3 
0 
Hard sulphurous black shale 
12 
0 
Hard shale . 
. 14 
0 
Soft sulphurous black shale 
7 
0 
Shale, with crystals of car- 
Hard shale, with chert 
12 
0 
bonate of lime . 
. 9 
6 
Black shale 
2 
0 
Grey shale . 
. 1 
0 
Very sulphurous black shale 
12 
0 
Greenish shales, with vein of 
Paler shade, with gypsum 
gypsum . 
. 20 
0 
veins .... 
4 
0 
Impure gypsum . 
. 9 
0 
Dark shale .... 
2 
0 
Pure gypsum 
. 4 
0 
Grey shale f{ Kimmeridge 
Impure gypsum . 
. 8 
0 
Clay,” very fossiliferous . 
378 
0 
Pure gypsum 
. 3 
0 
