1276

THE COLLIERY GUARDIAN.

June 13, 1913.

mission. One point he desired to emphasise was the
author’s preference for lead-covered, lead-sheathed
cables. He thought it was correct to say that there was
no more reliable piece of electrical apparatus than a
lead-sheathed and armoured cable. From a mining
point of view there might be some slight risk of
accident, but there was no safer method of transmitting
electricity than by a lead-sheathed and armoured cable.
In one place the author compared the relative prices of
three-core medium pressure paper and bitumen insulated
shaft cables. He wished to ask why the author
emphasised the shaft cables. Was there any difference
between shaft cables and roadway cables ? Personally
he had always thought a good shaft cable was a good
roadway cable and vice versa. Finally, he wished again
to point out that what was apparently the cheaper form
of cable, namely, the lead-sheathed cable, was in
addition, in his opinion, the safer.

Mr. A. F. W. Richards remarked that the author
did not give any comparison of twin- and three-core
cables. He quite agreed with the statement the author
made, that too much stress was very often laid on the
corrosive action of water. The author tabulated the
corrosive agents which were detrimental to bitumen, but
he must surely agree that the three causes to which he
alluded—caustic soda, lime and alkaline waters—were
just as bad for lead-covered cables as for bitumen cables.
One of the advantages of a bitumen cable was that it
was so flexible, resilient and safe to instal in awkward
.places, and in that respect it had a very great pull over
the lead-covered cable. It possessed also the great
advantage of a much simpler jointing. With regard to
the question of jointing, he could not agree with the
author that it was quite so simple. Everything appeared
to depend on the conductor and the fit, and it was
necessary to get hold of each individual wire in the
strand to get contact. He criticised several other points
in the paper, and said he did not care for the Elder
suspender, because it maintained the old trouble that
was so common of the eyelets drawing out.

Mr. Arthur Jacobs said it was generally admitted
by those who had seriously considered the subject that
aluminium showed to the best advantage on insulated
cables in connection with low-tension feeders, where the
cross-section of conductor was .relatively large. It was
also clear that, owing to the increased area of the
aluminium conductor, the effect of the aluminium was
very largely to negative any economy that might be
obtained through its employment. He was pleased,
therefore, to note the author’s conclusions that at the
average price of aluminium and copper conductors
there was a real economy in using aluminium in connec-
tion with that particulai’ class of cable. With regard
to the question of jointing, he was entirely in agreement
with the author’s conclusions. There was a good deal
in the making on the joint. In the making of the turn-
sleeve joint it was highly desirable to have the sleeve as
close as possible to the conductor, and not to make the
twists too short in making up the joint. He had no
doubt that the present price of aluminium was only of
a temporary character.

On the motion of Mr. Nelson, seconded by Mr.
Louis, it was resolved : “ That a hearty vote of thanks
be accorded to the president and council of the
Geological Society for their courtesy in allowing the
institution to use their rooms for the holding of the
present meeting.”

On the motion of Mr. G. J. Binns, seconded by Mr.
Pullorn, it was resolved: “ That the best thanks of
the institution be given to the owners of works to be
visited during the course of this meeting.”

On the motion of Mr. Tate, seconded by Mr.
Smythurst, a hearty vote of thanks was accorded to
the president for his services in the chair, and the
meeting terminated.

At the Waldorf Hotel, the same evening, the annual
dinner of the institution was held, under the presidency
of Dr. Garforth. Visits were also paid during the
meeting to the Mining Machinery Exhibition, the
Chingford Reservoir works of the Metropolitan Water
Board, and the works of the Beckton Gas Light and
Coke Company.

Royal Commission on Metalliferous Mines and Quarries.
—Meetings of the Royal Commission on Metalliferous Mines
and Quarries were held on Wednesday, Thursday and
Friday, June 4, 5 and 6, at Winchester House, 21, St.
James’s-square, S.W. Sir Henry Cunynghame, K.C.B.,

presided, and the other Commissioners present were:—Dr. i

J. S. Haldane, F.E.S., Mr. E. A. S. Eedmayne, C.B. (H.M. subord'nate

Chief Inspector of Mines), Mr. R. Arthur Thomas, Mr. R. T.
Jones, Mr. William Lewney and Mr. U. Lovett. Evidence
was given by Mr. G. G. Hewitt (mining engineer), and the
Commission had their report under consideration.

THE CONCEALED COALFIELD OF YORKSHIRE
AND NOTTINGHAMSHIRE.*

By Walcot Gibson, D.Sc.

In a preface Mr. J. J. H. Teall, the director of the
Survey, observes that in the present century the
development of the concealed coalfield by shafts and
borings has made rapid progress, and during the
re-survey of the Derbyshire and Nottinghamshire coal-
field between 1902 and 1909 especial attention was paid
to the examination of shaft sinkings and borings
through the permian and triassic rocks, not only of those
within the area under course of being surveyed, but also
of those in South Yorkshire. This volume—which is
the outcome of the investigation—is primarily intended
for those interested in proving the extension of the
visible coalfield. In it, therefore, facts of economic
importance have been accentuated, while results of
scientific bearing, though of much value, are less fully
discussed.

General Description.

The area shown in the sketch-map (fig. 1) of the
concealed part of the Yorkshire and Nottinghamshire
coalfield proved by the borings and shafts described in
this memoir amounts to about 1,200 square miles. It
can be regarded as consisting of a northern portion—
now generally known as the East Yorkshire coalfield—
situated between Doncaster and the River Ouse ; and of
a southern portion which extends over nearly the whole
of the county of Nottingham. The districts in which
boring explorations are most active are located chiefly
in the trench-like valley of the Trent from Nottingham
—where this important waterway becomes navigable—
to its confluence with the Humber. Development by
shaft sinking as well as by boring is chiefly taking place
in areas bordering the Don between Gooleand Doncaster,
the Aire east of Knottingley, and the Ouse below Selby.
A large area, as yet almost untouched, lies west of the
Trent between Newark and Gainsborough; south of the
Trent the extension of the coalfield has been proved in
several borings.

For many years it was thought that the coalseams
either did not continue east under the permian lime-
stone, or that the general eastward dip of the strata
would carry them to a depth too great for profitable
mining. So late, indeed, as the middle of last century
coalmining was restricted to the region lying west of
the permian limestone. In 1854 the Duke of Newcastle
commenced to sink two pits at Shireoaks, and early in
1859 the valuable Top Hard coal was cut at a depth of
1,530 ft., and proved to be 3 ft. 10 in. in thickness.
Development southward followed rapidly; and at the
present day most of the chief collieries of Nottingham-
shire are situated within the outcrop of the permian
limestone. In following the Top Hard coal to the east,
its eastward dip was found gradually to diminish. There
seemed, therefore, every prospect of finding the seam at
workable depths still further east beneath the red
triassic rocks which rest upon the permian formation in
this direction. Successful attempts were first made near
Nottingham, thence to the north and to the east, thus
gradually leading up to the most recent explorations.

Carboniferous.—A thickness of about 4,000 ft. of coal
measures has been proved in the concealed area, but the
greatest thickness proved in a single shaft or boring
amounts to 2,317 ft. (Maltby Colliery). The highest
measures have been pierced in two borings (Oxton,
Thurgarton), the lowest only in borings at Ruddington
and Kelham. All the other borings and shafts end in
middle coal measures. Though some workable coals
occur in the lower coal measures, the middle coal
measures contain the chief seams, one of which, named
the Top Hard coal in Nottinghamshire and Barnsley
coal in Yorkshire, is, from its superior quality, the
seam invariably sought after. The upper coal measures
do not possess workable seams, and are composed
chiefly of red sandstones and red marls.

Permian.—Where it reaches its full development in
the district, the magnesian limestone consists of two
beds of limestone separated and overlain by red marl.
The greatest thickness of the formation proved in any
one boring amounts to 622 ft. (Thorne).

Trias.—In persistence and superficial extent the trias
is the predominant rock system of the district, and
overspreads more than two-thirds of the coalfield. The
formation reaches a thickness of nearly 2,000 ft., and is
separable into two major divisions of different composi-
tion. The lower or hunter division consists mainly of
sands, soft sandstones and pebbly beds ; and the upper
or keuper, mainly of red clays or marls with somd
sandy beds which are thickest and most

persistently developed in the lower part.

Rhaetic.—Above the keuper, a thin series of deposits,

* From a Memoir of the Geological Survey, England and
i Wales.

termed rhaetic, consisting of black shales in the lower
part, overlain by grey shales with nodules and layers of
thin-bedded limestones, are usually classed with the
trias. The borings at Owthorpe and South Searle
enter the rhaetic beneath a few feet of liassic shales and
limestone: elsewhere the concealed coalfield has so far
not been proved further east than the outcrop of the
rhaetic.

The Carboniferous Rocks.

From the information obtained in the boring at
Thurgarton and elsewhere, and from the present know-
ledge of the underground structure of the area, it is
very improbable that the lower carboniferous will ever
be reached by any boring west of the Trent. Further,
it can be reasonably inferred that the permian and
triassic rocks will be found everywhere resting on the
coal measures and over the greater part of the area on
the middle coal measures, which would place the lower
carboniferous rocks below a depth of 4,000 ft.

The millstone grits, instead of dwindling to the
south-east, would appear to increase in thickness in this
direction, so that it is reasonable to postulate their
further extension to the south-east of Ruddington.

From the evidence obtained in the boring at Kelham,
near Newark, it appears that the millstone grits rise up
and abut against the permian rocks a few miles east of
the Trent.

Coal Measures.—The coal measures reach a thickness

of over 5,000 ft. In this long column of strata the
workable coals are most abundant and regular in the
middle, less frequent and more variable in the lower,
and absent in the upper part. The following classifica-
tion, which is based on the occurrence of the workable
coals, is the one usually adopted in the district:—

Upper coal measures
(500 ft.)

Middle coal measures
(2,300-3,300 ft.)

Lower coal measures
(1,200-1,600 ft.)

fRed sandstones and marls (Keele
I group).

I Grey sandstones with thin coals
I (Newcastle-under-Lyme group).

| Red marls and green grits (Etruria
L marl group).

r Grey shales and sandstones with
< the chief workable seams. Base,
C the Silkstone or Blackshale coal.
("Grey sandstones and shales with
j some workable seams. Base, the
rough rock or first millstone grit.

The latest schemes of classification are those based

on the vertical distribution of the fossil plants. In the
Yorkshire coalfield, Dr. Kidston, on the evidence of the
plants, has taken the horizon of the Silkstone coal as
the dividing line between the lower coal measures below
this coal and the middle coal measures between it and
the base of the red measures seen at Conisborough.
More recently he has proposed the term “ Lanarkian
series” to include the millstone grits and lower coal
measures, and the term “Westphalian series” for the
middle coal measures.* Above the “ Westphalian ” coal
measures and the equivalent middle coal measures of
other British coalfields, Dr. Kidston recognises a
“ transition series ” to which he gives the name of the
“ Staffordian series.” This includes the Etruria marl
and Newcastle-under-Lyme groups met with in the
boring at Thurgarton, while the sandstones and marls
of the Keele group are referred by Dr. Kidston to the
upper coal measures.

By some Continental geologists the Keele group is
included in the Westphalian division and it is considered
that the existence of any true upper coal measures
(Stephanian) in the sense in which the term is applied
in France, Belgium and Germany has not been proved
in Britain, and Dr. E. A. N. Arber has recently
expressed the same opinion.f It therefore appears
desirable to adhere to the classification given in the
table above, since it is the one adopted locally, and is of
practical utility. It should be kept in mind, however,
that above the highest (Keele) group a great thickness
of upper coal measures (Stephanian) occurs on the
Continent, and that, so far, any indication of their
being present on the east side of the Pennines is not
generally accepted.

As regards the accessibility of the coals, the boring
at Kelham* indicates that the lower seams of the middle
coal measures are well within the 4,000 ft. limit of
working in Nottinghamshire. In South Yorkshire,
from the evidence of the Thorne boring, it is reasonable
to infer that they will seldom exceed this depth ; while
the Top Hard coal in Nottinghamshire and Barnsley
seam in Yorkshire should be met with under 3,000 ft.

The absence of the upper coal measures at Kelham
shows that these barren measures do not occur over so
wide an area as might have been supposed from their
considerable thickness in the Thurgarton boring. The
large basin of the concealed Yorkshire and Nottingham -

* “ On the Divisions and Correlation of the Upper Portion
of the Coal Measures, with Special Reference to their
Development in the Midland Counties of England.” Quart
Journ. Geol. Soc., vol. Ixi., 1905, p. 308.

+ The Natural History of Coal, 1911, p. 26.