The South Staffordshire Coalfield/Chapter 5

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​

CHAPTER V.

Description of the Rocks—continued.

4. The Coal-Measures.

General Description.

The Coal-measures of North Staffordshire consist very largely of argillaceous (or clayey) materials, more or less mingled or alternated with arenaceous (or sandy) and carbonaceous (or coaly) substances. These different beds have various local names, of which the following is a nearly complete list:—

Argillaceous Materials.—Clunch,—a tough clay, breaking into blocks; sometimes rather sandy, generally grey or yellowish.
Binds,—shaly clay, close, smooth, compact, and splitting into regular lamine, generally blue, or some shade of grey. Clod, ground, earth,—earthy clay, generally of a blue or black colour.
Batt or bass,—highly carbonaceous[1] shale, commonly very compact, and splitting into the finest laminæ, almost invariably black, and often interstratified in layers with the coal.
Fire-clay,—clay having a certain definite i He of silica and alumina in its composition with but little admixture of metallic or earthy fluxes, so that on the application of heat it forms a nearly pure silicate of alumina, and therefore makes good fire-bricks. It is generally unctuous to the touch as soon as it is got, which "the other argillaceous beds rarely are. It is commonly a brownish grey, sometimes nearly black, but sometimes quite pale.

Arenaceous Materials. —The siliceous or arenaceous beds of the coal-measures have the following local names:—

Rock.[2]—All sandstones having any degree of hardness or toughness go under this name with the colliers.
Pebbley or bibbley rock,—sandstone with pebbles, conglomerate.
Rotch, or roach, is applied to sandstone when it is softer or more brittle than rock, so as to break easily into small fragments.
Peldon,—a very hard, smooth, compact, flinty stone, with conchoidal fracture.

​Some of these terms are used in composition to describe beds partaking of both characters, as—

⁠Rock-binds,—sandy shale or shaly sandstone.
⁠Clunch-rock,—hard sandy clay, &c. &c. &c.

Corbonaceous Materials.—There ia every gradation from a mere carbonaceous shale or batt through a " slummy," smutty, or batty coal to a perfectly pure bright coal with but very slight admixture of earthy matter.

The coals are usually bituminous, that is, they still retain mingled with the carbon such a proportion of hydrogen and oxygen as would allow of bitumen being formed from them by distillation. Some of them, indeed, are cannel coal, which blazes almost like a candle, and consumes away so as to leave only a little light, white, powdery ash.

Usually, however, the coals are of the variety known as Cherry coal, (see Ronald's and Richardson's "Chemical Technology," vol. i, p. 45,) being got in large blocks, not caking, easily lighted, and burning with a clear, cheerful flame, leaving a white ash, and no very large proportion of cinders.

Ironstones.—The ironstones are all clay ironstone, occurring either in thin regular seams or in layers of nodules, balls, or concretions. The principal kinds have now been analyzed in great detail under the direction of Dr. Percy. (See "The Iron Ores of Great Britain," Part II.)

Usually in all local descriptions of the Coal-measures of South Stafford, whenever the word " stone" is used, ironstone must be understood.

Parting and pricking mean the thin layers between the more important beds; they are generally some variety of clay.

Grouping of the Measures.—The way in which the various beds of clay, shale, sandstone, coal, and ironstone are interstratified with each other, may be seen by reference to the four published sheets of Vertical Sections. Nos. 16, 17, 18, and 26. The Coal-measures of South Staffordshire, as of most other districts, are made up of a great series of alternating beds of these materials,— all of them varying in thickness and extent. As a general rule, the beds of coal are more constant in thickness, and extend over wider areas, than the beds of other materials. Next in constancy and persistency to the coals come the finest grained rocks, such as the batts, and the finer varieties of fire-clay and clunch. The sandstones and coarser grained rocks are most capricious in their occurrence, and vary most suddenly in thickness and character.

Beds of coal are not only constant in thickness over very considerable areas, but also generally in quality and character. This is so much the case, that colliers and other persons who have been long engaged in handling the coals of a district will recognize detached blocks of different coals lying loose on the pit bank, even when taken to a distance of some miles from their own pits. They will name the seam each block came from, when to ​a less practised eye there seems no appreciable difference between them.

Changes, however, do occur both in the grouping and the quality of beds of coal. Changes in the grouping may occur either in the thickening or thinning of the measures between the coals, separating coals that were together, or bringing together those that were separate, or sometimes, but less frequently, even in the thickness of the coal-seams themselves, the very same becoming thicker in one place than another, or thinning out so as to occasionally disappear altogether. When, indeed, it becomes possible to trace a bed of coal over an indefinitely wide area, we must necessarily reach its termination by gradual thinning out in some direction or other.

Changes also occur in the quality and character of coals, so that sometimes, the very same bed or part of a bed, may within a comparatively short space become so altered in quality as to form quite a different variety of coal, and, of course, be no longer recognizable as the same, unless it be actually traceable by continuous working from one locality to the other, or can be referred to continuously traceable beds above or below it.

The South Staffordshire coal-field is distinguished from all others in the British Islands, and from most of those in the rest of the world, by the fact, that over a considerable part of its area a number of coals come together, resting one upon the other, with little or no interstratified shale or "parting" till they form a great seam of coal 30 feet in thickness. This has long been celebrated under the name of the Thick or Ten-yard Coal. The number of beds composing this remarkable compound seam are reckoned at from 10 to 14 in different places, according to the presence or absence of some of the beds, or of the separations between them. The "partings" of shale between the beds vary also occasionally in number and thickness, so that in some places the aggregate thickness of the coals is not more than 20 feet, with 10 feet of interstratified shales, &c.; while in others, the coals alone attain the dimensions of 36 feet, and with 3 feet of partings, make a total thickness of 39feet.

The Thick coal retains this structure, more or less completely, over all the district around Dudley as far as Bilston, Wednesbury, Oldbury, Halesowen, Brierly Hill, and Kingswinford. In two of these directions, however, namely, westwards towards Kingswinford, and northwards, towards Bilston, the remarkable phenomenon known as the "Flying reed" seems to point out the commencement of a great alteration in the grouping of its beds. The two upper beds of the Thick coal are separated from the rest gradually, but rapidly, by interposed shales and sandstones, so that in the space of a mile or thereabouts they form a distinct seam, called the "Flying reed," which, towards the west, becomes as much as 100 feet above the Thick coal, and more than 200, towards the north.

Towards the north, also, between Bilston and Wolverhampton, a separation occurs in the middle of the Thick coal, a bed of shale ​(sometimes called Hob and Jack), seven to ten feet thick, making its appearance between the "Foot coal" and the "Slips coal." These facts prepare us for the statement, of the truth of which good proof can now be given, that the change in the grouping of the beds was originally much more complete, even within the limits of the coal-field, and that the beds of coal which, coming together in the southern part of the field, form the Thick coal, are the very same beds, or some of them, which are worked now at Essington and Wyrley, and are there all more or less separated from each other by interposed shales and sandstones, so as to make a total thickness of over 300 feet. This change, from a thickness of thirty feet of coal only, to one in which thirty feet of coal are distributed among 300 feet of shales and sandstones, can be shown to have taken place within a horizontal distance not exceeding five miles. It is a kind of change quite familiar to those who are accustomed to trace any set of beds continuously along their strike, though it is not often that it can be so clearly proved and followed out in detail as in the present instance. Two of the coals below the Thick coal also undergo a similar separation towards the north.

Neither is this change in the grouping of the coals the only important change which occurs in the constitution of the field, for some of the lower beds of coal and ironstone which, in the part of the district between Wolverhampton and Walsall, are the richest and most important measures, dwindle away southwards towards Dudley, and farther south than that town have never been found at all in any workable form, though the measures of shale and sandstone in which they ought to lie have been pierced in search of them at several places.

These great changes in the constitution of the Coal-measures make it impossible to give any general section which shall be applicable in all its parts to any one locality. In the former edition of this Memoir this difficulty was evaded by giving, first, a list of the beds above the Thick coal, taken chiefly from the southern part of the field, and then a list of those below it, taken chiefly from the central and northern part. This plan, however, obscured the general view of the whole. It will, therefore, be better to give, first, a general section, compiled from the information to be obtained in the whole of the southern part of the coalfield from Bentley to Halesowen (Map 62. S.W.), and then another general and comparative section, applicable to the northern part of the district, from Bentley as far as Wyrley on the one side, and the Brown Hills on the other (Map 62. N.W.)

The first general section will include the mention of every workable bed of coal and ironstone in its proper place in the series, without regard to the locality in which it occurs. The second, while it agrees pretty nearly with the first in the lower measures (since each includes the Bentley district), will exhibit in the upper part the change before alluded to as occurring in the grouping of the coals forming the Thick coal, as well as some other changes in the lower beds.

​As a more easily remembered key to the structure of the district than that of the general section it may be as well to give the following abstract list of the principal workable coals in the southern district in descending order:—

  FT.
  Upper measures, maximum thickness about 800
1. Brooch coal about 4
  Intermediate measures varying in 25 pit sections from 87 to 218 feet mean 130
2. Thick coal about 30
  Intermediate measures varying in 33 pit sections from 7 to 35 feet the mean being 20
3. Heathen coal about 4
  Intermediate measures varying in 33 pit sections from 56 to 144 feet the mean being 109
4. New Mine coal about 8
  Intermediate measures varying in 43 pit sections from 2 feet to 35 feet the mean being 16
5. Fire-clay coal about 7
  Intermediate measures varying in 40 pit sections from 18 to 52 feet the mean being 30
6. Bottom coal about 12
  Lower measures maximum proved thickness 140
  1,310

This total of 1,300 feet is probably greater than the thickness of Coal-measures that ever existed at any one place in the southern half of the South Staffordshire coal-field.

General Section of the Central and Southern Part of the Coal Field.

  FT. . FT
1. [3]Beds above the Upper Sulphur coal 1a. The Halesowen sandstone group   600 to 800
1b. The Red, coal-measure clays
2. [4]Upper Sulphur coal   about 1
3. Intermediate measures   140
4. [4]Little or Two-foot coal   2
5. Intermediate measures   from 2 to 48
6. (I.) Brooch Coal   about 4
7. (I. 1.) Brooch binds, ironstone measures   from 7 to 20
8. [4]Herring coal[5] (not known north of Dudley   about 1
9. (I. 2.) Pins and Pennyearth ironstone measures[6]   from 7 to 30
10. Intermediate measures containing the sandstone known as the Thick coal rock   from„ 38 to 157 ​
11. (I. 3.) Broad earth, Catch earth, and Batt, containing the Ten-foot, and Backstone ironstones in the Pensnett district   from 6 to 14
12. T
h
i
c
k

c
o
a
l
. 		(II.) Hoofs coal or top floor   about 30
(III.) Top slipper, or Spires, or Spin coal
  These two form the Flying reed when separated from the coals below.
(IV.) Jays, or White coal
(V.) Lambs, or Floors, or Fine Floors coal
  These two are often either mentioned together under the name of White coal, or else the lower one is absent.
(VI.) Tow (tough) or Heath coal
(VII.) Benches coal (this bed is but rarely mentioned).
(VIII.) Brassils or Corns coal
(IX.) Foot coal, or Bottom Slipper, or Fine coal.
(X.) John coal, or Slips or Veins coal
(XI.) Stone, or Long coal
(XII.) Patchells coal (sometimes absent or not mentioned).
(XIII.) Sawyer or Springs coal
(XIV.) Slipper coal
(XV.) Bottom Benches, or Omfray (Humphrey), or Red, or Kid (Kick ?), or Holers coal.[7]
13. (I.4.) Pouncill batt, Blactery and Whitery, containing the Grains ironstone, and from sometimes the Whitery iron stone.[8]   from 2 to 8
14. (I.5.) Gubbin ironstone measures, sometimes called the Little, or Top, or Thick coal gubbin, sometimes the Black iron-stone   from„ 2 to 8
15. Table batt and intermediate measures   from„ 2 to 28
16. (XVI.) Heathen Coal   about 3
17. Intermediate measures (sometimes wanting)   from 0 to 43
18. (XVII) Rubble, or Lower Heathen coal, sometimes, when the measures above are wanting, forming the bottom part of the Heathen coal, sometimes itself wanting, when the measures above and below seem to be both present   from„ 2 to 4 ​
19. (I. 6.) Intermediate measures containing, at Bentley, the ironstones known as the Lambstone and Brownstone   from 10 to 33
20. (I. 7.) New Mine or White ironstone   from„ 2 to 10
21. (I. 8.) Measures containing the Penny-stone ironstone called also Bluestone or Cakes   from„ 10 to 25
22. (XIX.) Sulphur coal   from„ 2 to 9
23. Intermediate measures   from„ 3 to 99
24. (XX.) New Mine coal[9]   from„ 2 to 11
25. (I. 9.) Measures containing the Fireclay Balls ironstone occasionally   from„ 2 to 40
26. (XXI.) Fireclay coal (and partings)   from„ 1 to 14
27. Intermediate measures   from„ 2 to 10
28. (I. 10.) Getting Rock ironstone (occasional)   from„ 4 to 5
29. (I. 11.) Poor Robin ironstone measures   from„ 3 to 5
30. Intermediate measures, sometimes wanting   from„ 0 to 9
31. (I. 12.) Rough hills White ironstone (occasionally)   from„ 2 to 19
32. (XXII.) Bottom coal   from„ 3 to 12
33. Intermediate measures   from„ 5 to 30
34. (I. 13.) Gubbin and Balls ironstone, sometimes called the Great or Bottom Gubbin   from„ 3 to 10
35. Intermediate measures   from„ 18 to 50
36. (XXIII.) Singing or Mealy Grey coal (occasional)   from„ 2 to 4
37. Intermediate measures   from„ 16 to 50
38. (I. 14.) Blue Flats ironstone   from„ 2 to 9
39. Intermediate measures   from„ 10 to 14
40. (I. 15.) Silver Threads ironstone   from„ 4 to 7
41 Intermediate measures   from„ 6 to 15
42. (I. l6.) Diamonds ironstone   from„ 2 to 3
43. Lowest measures, maximum thickness known below the Diamonds ironstone   about 50

The variations in thickness, noted in the preceding general section do not take place indiscriminately, but chiefly according to a general rule, the least thickness being almost invariably found to the south, while the greater thicknesses come in regularly as we proceed northwards. There are, however, local exceptions to this statement, in the fact of a sudden thickening or thinning of any particular group of beds in a partial manner, and over a small area, with an immediate return to the normal thickness of the neighbourhood. The group of sandstones known as the Thick-coal rock, and some other sandstones, have these partial thickenings, while the shales between the New Mine and Fire-clay coals, sometimes, as in the Stowheath field, diminish quite unexpectedly to two feet, and then suddenly regain their usual dimensions of 30 or 40 feet. Sometimes, indeed, these two coals are so split up by partings, that when the thickness between ​them is small, it is not easy to determine which is the bottom part of the New Mine and which the upper part of the Fireclay.

Besides this original irregularity in the constitution of the coal-measure series, the present "lie and position" of the beds is such that the uppermost beds of all, the Halesowen sandstones namely, which come in far above the Upper Sulphur coal, are only now to be found around the southern margin of the field, where the beds dip to the south, while all the upper measures and the Thick coal itself have been removed by denudation from the district between Bilston and Bentley, where the lower beds gradually rise to the surface as we proceed towards the north. Neither do the Halesowen sandstones ever appear again further north although the great Bentley fault throws down the beds in that direction, so as to bring in the Thick coals and some of the beds above them, and although as we range to the north, the dip of the measures seems to be first west and then north-west.

We will now proceed to examine the general section of this northern part of the district, that namely, which lies north of the great Bentley fault, as far north as Cannock Chase. In order to make this general section at the same time a comparative one, and point out the locality whence each piece of information is derived, the following distinctive letters will be used; E. for the Essington district, W. for Wyrley, B for Bentley, and P. for Pelsall and the Brown Hills, while the average thickness will be that of all the places where the beds have been mentioned in the pit sections obtained.

General Section of the Coal-measures extending from Bentley to Essington and Wyrley on the West, and Pelsall and the Brown Hills on the East.

      Average thickness.
  FT. IN.
1. Various measures; 20 ft. E. 20 0
2. (I.) Coal; 2 ft. E. 2 0
3. Intermediate measures; 37 ft. E. 37 0
4. (II.) Coal; 1 ft. 9 in. E. 1 9
5. Intermediate measures, 10 ft. E. 10 0
6. (III.) Coal, 5 small coals with partings, 12 ft. 6 in. E. 12 6
7. Intermediate measures, 3 ft. E. 3 0
8. (IV.) Coal, 1 ft. E. 1 0
9. Intermediate measures, 66 ft. E. 66 0
10. (V.) Coal, 2 ft. E.; 1 ft. 9 in. W. 1 10
11. Intermediate measures, 32 ft. E.; 10 ft. W. 21 0
12. (VI.) Coal, 7 ft. 6 in. E.; (coals and partings 9 ft. 10 in.)W. 8 8
13. Intermediate, with a small coal, 57 ft. E.; 76 ft. W. 67 0
14. (VII.) Old Robins coal, 5 ft. 6 in. E.; 6 ft. 6 in. W. 6 0
15. Intermediate, 35 ft. E.; 18 ft. to 22 ft. W. 25 0
16. (VIII.) Wyrley Yard coal, with parting, 5 ft. E.; 3 ft. to 5 ft. 6 in. W. 4 0
17. Intermediate, including the Yard coal ironstone, 40 ft. E.; 36 ft. to 69 ft. W. 47 0
18. (IX.) Charles coal, 2 ft. 3 in. E.; 2 ft. 4 in. to 3 ft W. 2 6
19. Intermediate, 30 ft. E.; 24 ft. to 64 ft. W. 52 0 ​
20. (X.) Cannel coal, 3 ft. 8 in. E.; 4 ft. W. 3 11
21. Intermediate, 60 ft. E.; 54 ft. to 84 ft. W. 71 0
22. (XI.) Wyrley Brooch coal, 2ft. E.; 3 ft. 8 in. to 4 ft. W. 3 4
23. Intermediate, 3 ft. 6 in. E.; 1 ft. to 1 ft. 6 in. W. 1 8
24. (XII.) Benches coal, 7 in. E.; 2 ft. to 2 ft. 4 in. W. 2 0
25. Intermediate, with a 2 ft. coal, 74 E.; 40 to 48 ft. W. 54 0
26. (XIII.) [10] Wyrley Bottom or Eight-foot, Bentley Old Man's coal; 8 ft. 6 in. with partings E.; 6 ft. to 8 ft. W.; 9 ft. 10 in. B. 8 1
27. Intermediate, 38 ft. E.; 39 ft. to 46 ft. W.; 45 ft. to 61 ft. B. 46 0
28. (XXV.) [11] Essington Four-foot, or Bentley Hay coal, 4 ft. E.; 3 ft. W.; 5 ft. sometimes expanded by shale to 1 1 ft. B. 4 0
29. Intermediate, 51 ft. to 63 ft B. 54 0
30. (XV.) Heathen coal, 1 ft. 8 in. to 3 ft. B.; 2 ft. 6 in. P. 2 0
31. Intermediate, 44 ft. to 56 ft. B.; 61 ft. P. 50 0
32. (XVI.) Sulphur coal, 1 ft. 6 in. to 4 ft. B. 1 9
33. Intermediate, 21 ft. to 52 ft. B.; 32 ft. to 52 ft. P. 43 0
34. (XVII.) Yard coal of Pelsall, 3 ft. to 3 ft. 6 in. B.; 2 ft. 9 in. to 3 ft. 8 in. P. 3 2
35. Intermediate, 31 ft. to 46 ft. B.; 26 ft. to 50 ft. P. 40 0
36. (XVIII.) Bass coal of Pelsall, 4 ft. to 6 ft. B.; 3 ft. to 6 ft. P. 5 10
37. Intermediate, 21 ft. to 35 ft. B.; 29 ft. to 39 ft. P. 31 0
38. (XIX.) Fireclay or Cinder coal, 3 ft. 10 in. to 6 ft. 8 in. B.; 3 ft. 2 in. to 5 ft. P. 4 6
39. Intermediate, 21 ft. to 46 ft. B.; 21 ft. to 49 ft. P. 33 0
40. (XX.) Upper part of Bottom coal, or Shallow coal, 2 ft. to 7 ft. 9 in. B.; 4 ft. to 7 ft. P. 5 4
41. Intermediate, 8 in. to 8 ft. B.;[12] 38 ft. to 51 ft. P. (average of latter) 46 0
42. (XXI.) Lower part of Bottom, or Deep coal, 2 ft. 9 in. to 4 ft. 8 in. B.; 5 ft. to 15 ft. P.[13] 6 8
43. Measures between the Bottom coal and the Silurian shale, 137 ft. B. 137 0
  1,053 0

​

​If we compared the two general sections now given, on the supposition that the Thick coal of the first was but one coal, we should have only 7 or 8 workable coals in that section to contrast with 21 in the other. By taking into account that the Thick coal is made up in reality of 12 to 14 separate coals, we at once get the fact that the number of coals are in reality nearly the same in both sections. The difference in the two series is then seen to be the result of variations in the other materials, namely, the shales and sandstones with which the coals are interstratified.

It may very well be doubted whether any single bed of coal is ever more than two or three feet in thickness, and we may therefore take it for granted, that every bed which exceeds that thickness over any considerable space is in reality a compound seam made up of two or more beds resting on each other, with or without "partings" of shale, &c, between them. Not only then are many of the beds which are spoken of under one name in the southern part of the district compound seams, but several of those in the northern district also. We may look upon the seams numbered III, VI, VII, VIII, XIII, and XXI, in the second general section as undoubtedly compound seams, liable at any place to be separated into two by interposed shale and sandstone. Some of the others may also be compound seams.

In comparing the two general sections we must recollect that the second does not include any of the 600 or 800 feet of upper measures which form the top of the first, and we shall then see that the bulk of the coal-bearing beds in the second is much greater than the bulk of the coal-bearing beds in the first. Since, however, the quantity of coal disseminated through that bulk is nearly the same in both, or at least is but slightly preponderate in the second, it follows that the increase is in the shales and sandstones interstratified with the coals. Since, moreover, the lower beds are the same in both sections, it follows that the beds above them, those about the Thick coal, are on the same geological horizon, and that the Thick coal of the first is split up somehow into the separated beds of coal to be found in the second.

In Plate I. Figure 1 will be found a representation of this splitting up of the Thick coal and other coals towards the north in a diagrammatic form. The constitution of the beds south of Bilston (which we may call the south central portion of the coal-field) is shown on the one hand in a vertical section on a scale of 120 feet to an inch, and that of the beds at Bentley and north of it, on the other hand, in a similar vertical section on the same scale, each section being a mean or average section deduced from a considerable number of actual pit sections.

The coals known as the Heathen and Sulphur are common to the two sections, the Heathen being assumed as the horizontal datum line.

The Fire-clay and Bottom coals are also common to the two sections being worked continuously from Bilston to Bentley, and thence to Pelsall.

​Just at the south end of Pelsall Heath, the Bottom coal, which up to that pot has been worked continuously as a single twelve-foot coal, begins to separate into two coals, which about a mile or so farther north are as much as 15 yards (45 feet) apart. These two coals were formerly gotten along their outcrop at the Brown Fills, under the name of the Shallow and the Deep coal. The Deep coal itself is also, a little farther north, beginning to separate into two coals.

The Fire-clay coal has been worked continuously from Bilston up to Bentley, and thence by Goscott to Pelsall, but on reaching the latter place it apparently begins to change its quality and character, and further north is known only as the Cinder coal.

The New Mine coal crops out a little before it reaches so far north as the Great Bentley fault, and when thrown in by that fault, it is found to be separated into two, called at Bentley the Three-foot and Five-foot, but known farther north as the Yard and the Bass coal. That these two coals are in reality the two separated parts of the New Mine coal is shown by the fact that at Bentley they have the Sulphur and Heathen coals next above them, and the Fire-clay coal next below them.

With this tendency to split up into separate coals as we proceed towards the north, clearly proved to exist in the lower beds which run continuously in the ground, we can the more readily allow the probability of a similar tendency in the upper beds, which now only occur in localities more widely separated from each other in consequence of the removal of large portions of the measures by the denudation that has acted over the intermediate space.

In consequence of the denudation having removed so much of the upper measures it is difficult, perhaps impossible, to identify the beds of those upper parts of the two districts with the same precision that we can the beds in the lower measures. It is, however, very remarkable that if we add together the average thickness of the coals in the Wyrley and Essington district, commencing with the Old Robins coal, and including the Essington four-foot or Bentley Hay coal, which there lies next above the Heathen coal, we shall, if we omit the partings, get a thickness of a little over thirty feet (about thirty-three feet), which agrees quite as closely with that of the Thick coal as we could expect.

Whether the Brooch coal of the district south of Bilston, be represented by the Essington sixth coal, or whether the fifth and sixth coals of that locality be new coals, and the third and fourth represent the Brooch, is perhaps a moot point.

If the Old Robins coal be really the top of the Thick coal, or the same as the Flying reed coal, then the Essington sixth coal is at rather a less height above it than the Brooch is above the Thick coal in the southern part of the field. Bearing in mind, however, the tendency to thicken and increase towards the north which the measures below exhibit, we should expect the height to be greater, and should be more inclined, perhaps, to look upon the fifth and sixth coals of Essington, either as themselves the representatives of the Flying-reed, or upper part of the Thick coal, (which will ​then not merely be separated by shales, but have a greater thickness of coal than it generally has farther south,) or else consider them as new coals not represented at all in the southern part of the field.

Whatever may be the truth with regard to those points of detail, the general fact of the beds at Essington. Wyrley, and Bentley, from the Old Robins coal down to Bentley Hay coal inclusive, being the representatives of the Thick coal can no longer be doubtful.

It appears that the materials which formed the shales and sandstone, &c. were deposited abundantly and frequently towards the north, but that some of them gradually became less and less towards the south, so that in many cases they finally came altogether to an end in the latter direction, while the coals were deposited equally, or nearly go, over both areas.

The fact now established is one of considerable interest, both as regards the practical working of this and other coal-fields, and as bearing on the theoretical explanation of the origin and formation of coal.

Note on the Fossils, by J. W. Salter, Esq.

The fossils of the ironstones as a whole very much resemble those of the Coalbrooke Dale coal-field. There is the same intermixture of marine shells, shark-like fish, and a few land plants, with a considerable number of unio-like shells (Anthracosia), too imperfect for determination in most cases. One species, however, is the A. bipennis. Brown, found, both here and in Flintshire, in the coal itself. The marine shells are quite the same as those of the "Pennystone" of Coalbrooke Dale, but they are fewer in number,

The following may be considered characteristic of the ironstones:— Discina (Orbicula) nitida of Phillips; Producta scabricula, Sowerby; a Lingula, which appears to be the L. elliptica of Phillips; Conularia guadrisulcata, and the two species of Myalina figured by Prestwich, viz. M. quadrata and M. carinata. The Aviculopecten scalaris, Sowerby, is rare. With these are abundance of the large fish defences, called Gyracanthus formosus, Agass.; scales of a large Holoptychius; the Megalicthys Hibberti; and Cochliodus. (Pæcilodus angustus occurs in bastard coal at the Fens colliery.) There are also traces of Annelides, and the usual plants, Lepidodendron, Calamites, &c., occur.

The localities from which these fossils have been obtained are;—the pit banks three-quarters of a mile N.E, of Portway Hall near Oldbury, and the Factory north of that place. The Producta and Conularia are abundant at the former, and the large Mytilus-like bivalves (Myalina), with the Lingula and Fish, at the latter.

South and south-west of Dudley, at Queen's Cross, Holoptychius and Myalina occur in the Gubbin ironstone; and at the Buffery ironworks the large Gyracanthus formosus. The Fens south-west of Dudley have a few shells in the carbonaceous bands, and also a fish-palate, Pecilodus angustus, a species equally characteristic of similar beds (the top coal) in Coalbrooke Dale. It is also found in coal in Flintshire.

Further west. Kingswinford colliery affords only Anthracosia, Modiola, and the Gyracanthus formosus. At Moor Lane, Brierly Hill, the Holoptychius and Lingula.

Further south, near Oldswinford, White Hall colliery has the usual Brachiopods, Lingula and Discina, with Conularia, Anthracosia bipennis (in coal), and the Aviculopecten scalaris.

Bare Moor colliery, only Brachiopods, Productæ, &c.

  1. ↑ It has been usual hitherto to call this "bituminous" shale, an incorrect term, inasmuch as, though it contains the components of bitumen, it does not contain that substance itself; one might almost as well in speaking of a sack of malt call it a barrel of ale.
  2. ↑ Under the term "rock" the miners likewise include all kinds of trap which occur in the district, using generally the distinctive terms "green rock" and "white rock," according to the colour. The only practical ambiguity that arises from this confusion of terms is in the case of the "white rock;" as, when that term is used, it is sometimes doubtful whether white sandstone or white trap is meant.
  3. ↑ Each group of beds is numbered in consecutive order, the workable coals having an additional number in Roman figures, and the ironstones an additional number with I, before it.
  4. ↑ 4.0 4.1 4.2 The coals thus marked are not numbered, as they have never yet been worked.
  5. ↑ So called from containing many dorsal spines of fish, called herring bones by the colliers.
  6. ↑ These ironstones are occasionally rich in the remains of fishes.
  7. ↑ Beds numbered as XV., XIV., XIII, XI., X., IX., VIII., VI., with either IV., or IV. and V. grouped as the White coal, are always present wherever the Thick coal is at all in the normal condition ; where III. and II. have gone off as the Flying reed, the White coal is always the top measure ; the beds numbered VII. and XII. are often omitted, either being absent or being grouped with the one above or below them.
  8. ↑ About Bentley there is an ironstone in these measures which is there called the Bind ironstone, and it has a coal called the Bind coal associated with it, which is sometimes 14 inches thick.
  9. ↑ The New Mine coal is completely separated into two coals at Bentley, there called the Three-foot and the Five-foot, with 33 feet of shale and sandstone, containing ironstone between them.
  10. ↑ This, which is the lowest coal hitherto worked at Wyriey, is the uppermost coal of all in the Bentley district, only coming into the ground, here and there, when the lower beds dip deep enough to allow it to do so.
  11. ↑ This coal has been sunk into at Essington, and has also been twice reached, once by boring, and another time by sinking, near Wyrley, where it was found to be only 3 feet thick. The finding of this coal there at the proper distance below the so-called Bottom coal of Wyrley lends a strong support to the identification of that coal with the Old Man's coal of Bentley.
  12. ↑ In the Bentley district the Bottom coal is still looked upon and worked as one seam, even when the central parting is several feet thick. It is only N.E. of Goscott that the two parts become so widely separated that they are worked as two beds under the names of the Shallow and the Deep coal. Between Bentley and Goscott the Bottom coal is in one place even called the Thick coal, being the thickest bed known thereabouts.
  13. ↑ Where the Deep coal thickens to 12 or 15 feet it is in consequence of a considerable parting separating the bottom part of it from the rest. It is probable that further north this separation will become so considerable that the coals will be separately gotten and receive separate names.
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