I am very grateful to Dr Lloyd Boardman, formerly head of Geology for British Coal, Western Region, for access to his original article which is available via this link.
The North Staffordshire coalfield was formed during the Carboniferous geological period, about 300 million years ago when it was laid down from decaying vegetable matter, forming peaty deposits. These peat deposits turned into coal measures through processes involving pressure, heat and earth movements over a very long period of time.
The process was repeated time after time so that many coal seams (about 25 are workable) are interspersed between layers of shales and sandstones.
Other usable minerals were also laid down, including ironstone.
And the “Etruria Marl”, prized as a raw material in the manufacture of bricks and tiles, formerly a staple industry of Stoke-on-Trent.
The coal and other mineral seams in North Staffordshire formed an integral part in the creation of the ceramics industry in what became to be known as “The Potteries”.
The North Staffordshire coalfield is structurally complex with steeply dipping seams and complex faulting that has added to the difficulty and expense of working the coal. Some of the coal beds (“The “Rearers”) can be near 90 degrees to the horizontal.
These are the coal seams, thicknesses and the depth of the seam (in feet and inches), as encountered at the former Hanley Deep coal mine, located at what is now the Central Forest Park in Hanley.
| Seam | Thickness (Feet) | Depth (Feet) |
|---|---|---|
| WINGHAY | 4′ 6″ | 129 |
| BILLY COAL | 1′ 6″ | 275 |
| ROWHURST + RIDER | 12′ 0″ | 508 |
| BURNWOOD | 5′ 2″ | 589 |
| TWIST | 4′ 0″ | 650 |
| GRANVILLE’S (Birchenwood) | 7′ 0″ | 1120 |
| MOSS | 3′ 10″ | 1190 |
| MOSS CANNEL | 3′ 0″ | 1225 |
| FIVE FEET | 2′ 3″ | 1272 |
| YARD | 3′ 6″ | 1409 |
| RAGMAN | 3′ 10″ | 1432 |
| ROUGH SEVEN FEET | 2′ 3″ | 1448 |
| HAMS | 4′ 6″ | 1517 |
| BELLRINGER | 2′ 6″ | 1646 |
| TEN FEET | 5′ 6″ | 1786 |
| BOWLING ALLEY | 4′ 3″ | 1942 |
| HOLLY LANE | 3′ 6″ | 2036 |
| HARDMINE | 4′ 6″ | 2126 |
| BANBURY | 3′ 6″ | 2418 |
| COCKSHEAD | 7′ 4″ | 2583 |
In some cases it is straightforward to derive why a seam is so-called; such as the Five Feet, Yard or Ten Feet, although none of those seams at Hanley Deep Pit match their descriptions.
Some seams are named after locations, such as Holly Lane, or their characteristics, such as Hardmine.
Others are more difficult to define, although it’s thought that Cockshead reflects the rainbow sheen of colours of the male hen, as shown in this Charles William Brown painting.
©️ copyright, The Potteries Museum & Art Gallery, Stoke-on-Trent
For more information about the artist, Charles William Brown, click on the image above.