THE COLLIERY GUARDIAN

and journal of the coal and iron trades.

Vol. CV.

FRIDAY, FEBRUARY 21, 1913.

No. 2721.

SOUTH STAFFORDSHIRE AND WARWICK-
SHIRE INSTITUTE OF MINING ENGINEERS.

A meeting of this institute was held at the University,
Birmingham, on February 17, the President (Dr. J.
Cadman) in the chair. There was a large attendance of
members and visitors.

The President proposed a vote of condolence with
the relatives of the late Mr. G. A. Hurst, who had been
a member of the institute since 1895. This was passed
in silence, the members standing.

The following gentlemen, having been approved by
the council, were elected members:—Mr. H. P. Bell,
Pendlebury Colliery, Bentley, Walsall; Mr. H. W.
Parkin, Bloxwich Colliery, near Walsall; Mr. W. S.
Rowell, Windsdr-place, Shrewsbury.

The Westerly Extension of the South Staffordshire
Coalfield.

The President said that it was a great pleasure to
him to introduce Dr. Walcot Gibson to read his paper
on “ A Boring for Coal at Claverley, near Bridgnorth,
and its Bearing on the Extension Westwards of the
South Staffordshire Coalfield.”

Dr. Gibson read his paper, which was illustrated by
large geological diagrams, as follows :—

Permission to make a thorough examination of the cores
of this important boring was generously granted by Mr.
Edward Parry. Subsequently the boring was examined by
members of the Geological Survey, and will be described in
greater detail when the results are completed. The following
account is confined to a record of the main facts likely to
prove of service to those engaged in explorations to the
west of the present coalfield.

On the western side of the South Staffordshire coalfield

the productive coal measures come into contact with a thick
mass of barren red carboniferous rocks, beneath which they
have been proved within limited distances of the visible
coalfield at Baggeridge, Holly Bank, and Four Ashes.
Along the southern margins of the coalfield the red strata
(without workable seams) conformably succeed the grey
rocks of the Thick Coal group. They arrange themselves
into three groups in descending order, as follow:—

_________~ C Bed sandstone and marls, with thin
Keele group (lower \	f

permian), 800 ft. 1 « . ® .05. g ®y aa Dlue
F J	(. Spirorbis limestones.

TTalAsowen sand- ( Grey sandstones and shales. Two or
omnn qoa ) more thin coals, and a band of pale
g P* " j blue Spirorbis limestone towards

4UU tees.	the summit

/'Red marls, with lenticular bands of
Brick clay or Espley \ grey marls and bands of coarse
group, 250-300 feet, j green grits, frequently conglomer-

C atic.

Above the Keele group there comes a series of red sand-
stones, marls, conglomerates, and breccias, exceeding 500 ft-
in thickness, of which the relationship to the Keele group
is uncertain, although here, as elsewhere, they are found
only where the latter is fully developed. They are succeeded
unconformably by the triassic sandstones and conglomerates.

In the northern part of the Cannock Chase area the
whole of the barren, and a considerable thickness of the
productive measures, were denuded before the deposition of
the triassic sandstones and conglomerates. The folding
and major faulting of the carboniferous rocks were also of
pre-triassic date. Between Cannock and Essington, along
the western boundary of the coalfield, the unfaulted trias
rests on the faulted and folded brick-clay group; and near
Wolverhampton on the Keele group.

The great discordance between the trias and the carboni-
ferous formations which thus prevails over the visible
coalfield may be expected to extend in a greater or less
degree over the concealed coalfield; indeed, its future
development depends upon a post-carboniferous but pre-
triassic denudation of sufficient magnitude to have removed
a part, and in places the whole, of the barren measures; for,
if these occur in their entirety, then over a wide area the
workable coals lie hopelessly beyond reach.

In every attempt to prove the depth to the seams beneath
the unconformable trias, which stretches as a broad sheet
composed of lower sandstones (bunter and keuper) and marl
(keuper), between the South Staffordshire coalfield and that
of Shropshire, it is’obviously useful to know the characters
by which a lower can be distinguished from a higher
position in the barren measures. It is also important to

ascertain whether the conformability between the upper
unproductive and lower productive strata will extend over
the concealed, as it apparently does over the visible, coal-
field. A boring near Claverley, situated midway between
the coalfields of South Staffordshire and Shropshire, affords
much of the requisite information.

The site chosen for the experimental boring is situated
in latitude 52 degs. 31 mins. 10 secs, and longitude
2 degs. 17 mins. 30 secs., or about G miles nearly due south
of Claverley village, and about 5 miles south-east of
Bridgnorth. This district, including Enville, was selected
by Prof. Edward Hull as typical of the development of the
lower permian formation. The local arrangement {around
Gatacre and Bobbington is, according to Mr. W. Wickham
King, in descending sequence, as follows:—
Upper permian, 170ft.... { S and breccia.

f Marls.

Middle permian, 330ft.... j Sandstone, calcareous sand-
(. stone, and a little mar].

Lower permian, 800ft.... ) Marie and sandstones.

(Keele group) .	1

The boring starts within the outcrop of the upper
permian, the summit of which, owing to the overlap of
trias, is not seen. The total thickness of red strata
penetrated before grey measures were reached amounted to
1,240 ft. From the surface to a depth of 185| ft. the beds
are assigned to the upper permian group; from this depth
to 472 ft. the character of the strata accords with that of
middle permian group. The beds below down to 1,240 ft.
undoubtedly represent the Keele group. The upper permian
consists of bright-red marls and red sandstones of bunter
type, with two bands of deep-red breccias (“ conglomerates *
of the record) at 130 ft. and 179 ft. respectively. The
middle permian is essentially a sandy series, with subordinate
bands of crimson marl. The sandstones are red-brown or
white in colour, highly though irregularly calcareous, the
cementing material forming the very hard calcareous
nodular concretions, which give the false impression of a
conglomerate. This is particularly the case with the two
bands of “ conglomerate ” towards the top and at the
bottom of the group. In the red marls, circular and
irregular green patches (,f fish eyes ”) are common. These
markings are not peculiar to the permian rocks, but are
met with in red strata of various geological ages.

In the Keele group, between 472 and 1,240 ft., red marls
predominate. A few thin beds of red sandstone are also
present, with thicker bands of a lavender colour towards
the base. The marls are laminated, and in places somewhat
sandy, and are not unlike those of the middle permian;
while other bands of deep red, ochreous and purple
unstratified clays bear a close lithological resemblance to
the marls of the brick-clay group, but there are no indica-
tions of rocks of Espley type to connect them with this
subdivision of the barren measures. In the record mention
is frequently made of the occurrence of “ white nodules,”
but the term is vicariously applied. Thus those at 488| ft.
and 972 ft. respectively consist of rounded blocks of grey
limestone containing Spirorbis; while in the red marls with
white nodules, commencing at 758 ft., the description
includes a thin bed of dark Spirorbis limestone near the
base, as well as calcareous concretions without Spirorbis
scattered throughout the body of the marls; in other cases,
the term is applied to green patches of marl, and to
concretions of various kinds.

Below 1,240 ft. to a depth of 1,604 ft. the grey sandstones
and shales, with thin coals, can be confidently placed in the
Halesowen sandstone group. The bed of pale-blue Spirorbis
limestone that occurs near the summit of the group in
Illey Brook, near Halesowen, is apparently absent, although
the cores were specially examined for any indications of its
presence.

The grey sandstones and marls below 1,604 ft. pass
gradually downwards into deep red and purple marls, which,
from the occurrence of coarse green grits 'and breccias of a
typical Espley type, evidently belong to the brick-clay or
Espley group, as developed around Old Hill and Oldbury
and elsewhere in the visible coalfield. Mottled clays, with
intercalations of grey and black shale, continue to a depth
of 1,863 ft.; but, since in a black shale at 1,811 ft. 8 in.
there occurs the marine shell Lingula (which is unknown in
the red measures, though not uncommon in the productive
coal measures), it appears that the lowest mottled marls
should be excluded from the brick-clay group.

That the grey measures below 1,863 ft. belong to the
productive coal measures will not, the writer thinks, be
disputed ; but, in the absence of any recognisable seam of
coal or other distinctive bed, it is not safe to correlate the
sequence with that of the Forest of Wyre on the west, or
that of South Staffordshire on the east. Possibly the
sequence is not complete, and part is faulted or washed out.
The igneous rock (an olivine-dolerite at a depth of 1,937 ft.)
may have come up along a fault, although it is impossible
to state whether the igneous rock occurs in dyke form or as
a sheet.

At 2,190 ft. the carboniferous rocks, without any indica-
tions of a basal conglomerate, rest on silurian shales and,
calcareous beds containing Atrypa recticularis in abundance,
with other representative silurian fossils.

From the silurian upwards, the inclination of the strata
shows no change; and, so far as it is possible to measure, it
remains nearly horizontal. There are no signs of faulting,
and, with the exception of slight attenuation of the brick-
clays, the thickness of the groups above the productive
measures so closely agrees with that at the southern end of
the coalfield as to preclude faulting of any magnitude.

The chief fossils consist of plant remains, which occur in
abundance in the Halesowen sandstone group, and in the
grey measures below the brick-clay group. They are not
uncommon in the Keele group, but are rare, fragmentary,
and indeterminable in the sandstones and marls above
472 ft. With the exception of a species of Palaeoxyris in red
marls at a depth’of 647 ft., and of a Walchia at 850 ft. and
1,095 ft. respectively, the plants are not known in rocks
later than the coal measures. The plants in and above the
Halesowen sandstone group indicate a higher position than
those below the brick-clay group. Recently, Mr. W. H.
Hardaker* has published his discovery of amphibian or
reptilian footprints in the permian rocks of Hamstead,
which appear to correspond in stratigraphical position with
the middle permian of the Enville or Clent district.

The boring shows that in the typical district of Enville,,
the grouping of the strata above the productive coal
measures agrees very closely with the succession along the
southern margin of the South Staffordshire coalfield. At
Claverley, as in the Halesowen district, there is no sign of
any discordance, either in change of dip or in abrupt
deposition between the productive coal measures and the
brick-clay group, which also merges upwards into the
Halesowen sandstones, and these into the Keele group. A
similar passage of grey into red measures with Spirorbis
limestone is described by Mr. T. C. Can trill in the Forest of
Wyre. The occurrence of Espley rocks amidst red clays
succeeding the productive coal measures is repeated on the
eastern side of the South Staffordshire coalfield at Langley
and Sandwell Park, where also the brick-clays pass upwards
into grey sandstones and shales, comparable with the
Halesowen sandstones containing bands of dark Spirorbis
limestone.

In North Staffordshire a conformable upward sequence of
(1) |red clays with green grits (Etruria marls), (2) grey
sandstones and shales (Newcastle group), and (3) red sand-
stones and marls (Keele group), delineates very faithfully
the structure of that complicated region. It is, therefore
reasonable to surmise that the barren red measures arrange
themselves in the same order in the area lying west of the
South Staffordshire coalfield as they do elsewhere.

A description of the strata passed through is given in
the form of an appendix.

Discussion.

The President said they had had a most important
paper, read in a very fascinating way. If his conclusions
were correct, and the coalfield was found both east and
west, he (the president) thought the district would not
be found wanting in enterprise in following up such
geological evidence as Dr. Gibson had put before them.
They knew that on the west and on the east of the
Shropshire field great denudations had been made, and
whether those denudations were all as they were shown
on the map was a matter still to be proved.

Prof. C. Lapworth, LL.D., F.R.S., said he had
listened to the paper with the greatest interest. He
would urge on those present who had sections of that

* “ The Discovery of a Fossil-bearing Horizon in the
Permian Rocks of Hamstead Quarries, near Birmingham,” by
Walter Henry Hardaker, Quarterly Journal of the Geological
Society of London, 1912, vol. xxviii., pages 639-684.