Blackbrook Archaeology; The Return
by Peter Keen

The search for answers has continued at the site of Stanley Slitting Mill at Blackbrook.

Just a quick recap; the site of the Mill lies in the valley of the Black Brook, near its confluence with a narrow stream valley which could be easily dammed to create a water power source. The stream, together with a small leet from Blackbrook, and later Carr Mill Dam, provided the water. An iron slitting Mill was built to transform the iron ingots from Carr Mill Furnace into thin iron rods for the local nail making industry. Later the mill was substantially altered into a corn mill which was its last use before demolition. At all stages of the site's active life it is probable that the Sankey Canal was used both to bring in raw materials and to distribute finished products.

In early August 2008 a programme of excavations was arranged and carried out utilising the services of Liverpool Museum's Archaeology Department, a number of archaeology students and a group of local volunteers, some of whom have now been working periodically on the site over the last three years. Having successfully applied for lottery funding, St Helens MBC planned a week of excavations to develop the story of the site, probably the first industrial complex within the borough, and therefore of major historical significance. A small digger was brought in to strip off whatever over-burden remained from the previous investigations and specific sites were identified for investigation by hand digging by small teams.

Foundation walls revealed a whole series of rectangular shapes, some of which would have been interior floors and others exterior paved areas. In some cases a clear succession of surfaces was present, the sandstone slabs of the corn mill being bedded onto a thick layer of sand which covered a floor of crushed mortar and stone mix, then a layer of cinders before the natural clay layer was reached. This was by no means original, in that the iron slitting mill might have had a different floor surface which was removed when the corn mill was under construction. Here and there were simple brick drains laid across what were probably exterior yards.

The 1982 work had uncovered a wheel pit at one side of the main building (north), but the usual set up for slitting mill was for two water wheels since one alone would not have been bars of iron repeatedly through the rollers to achieve the correct cross section.

Where then was the second wheel pit?

Part of the previous excavation included a geophysical survey and a magnetometer survey of the site. These, plus some small scale explorations suggested the best location to dig and work commenced. Over the next three days the massive walls of the second wheel pit (south) emerged, with a clear indication of which sections of walling belonged to the iron slitting mill and which belonged to the later corn mill, literally built upon its foundations.

Of larger dimensions to the first wheel pit, the second one had a few surprises for the diggers. Cut into some of the large sandstone blocks were a number of masons' marks, usually chiselled into stones to indicate the maker's identity and output and thus fix his wage. On the north face were a vertical cross with serifs at the ends (left) and a symbol which strongly resembled a weather vane (right). Both these symbols were also found on the faces of stones built into the dam, indicating that they were probably built at the same time.  On the south face of the pit is another mason's mark, two triangles arranged to form a diamond shape. On the dam wall was also found a mark which is a variation of that marking O.S. datum heights. It could be concluded that at least four stone cutters were at work during the construction of the mill and its dam, although it must be said that most of the surviving structures are of brick and would not have required the services of a mason. Perhaps the stones had been salvaged from a building in the vicinity which had been demolished, possibly elsewhere on the Gerard Estate to which the site belonged.

The new information did not end there. Over time, water wheels became increasingly eccentric as their axles and mountings wore so that instead of spinning centrally in their pits they would veer to one side. In water mills all over the country the results of this veering can be seen in the scour marks made by the wheels as they wore away the pit sides.  Sure enough there were scour marks in the sandstone blocks of the southern wheel pit at Blackbrook, the curvature suggesting a wheel of approximately 15 to 16 feet in diameter.

There are two types of sandstone on site, the large red sandstone blocks which form the foundations of what were probably the slitting mill, and a tougher yellow sandstone which has been used to shape building blocks, some bearing the masons' marks mentioned above. As with most building projects of the time the stone was probably from local quarries, and was brought to the site via the Sankey Canal.

Once the water has been used to turn the wheel, it has to go somewhere, usually along a tail race back to the stream or river from which it originally came. The 1982 investigation had located a sturdy brick built culvert leading from the northern wheel pit into Blackbrook. Its junction with the wheel pit has deteriorated through time and vandalism but it seems likely that there was once a stone wall across the end of the pit pierced by an arch leading into the culvert. None of this survives other than the brickwork of the culvert. This is still in fact the major exit path for water entering the site of the slitting mill.

The southern wheel pit has a stone wall at its western end with an arched shape (left) clearly visible approximately one metre down, so it would seem that there is a second culvert below the present path which once carried the southern tail race.

Unfortunately there was insufficient time to allow further investigation and the wheel pit was filled in until such time as the site can be properly investigated. Undershot water wheels were known to be inefficient and the lack of evidence suggests that the water wheels at Stanley were overshot, powered from timber chutes carried on timber trestles across from the dam at a fairly high level. A sluice is marked on the first O.S.map which would support this assumption.

Some of the archaeological students spent much of their time sketching the lay out of the buildings' foundations which had been uncovered, drawing every brick and stone, whilst one of the archaeologists made a detailed study of the front face of the dam in an attempt to work out its history. There is little evidence of the original structure of the dam left. The 1982 investigation revealed a clay infill supported by stone and brick walls. This evidently gave trouble and extensive buttresses were built to strengthen it but these still proved inadequate and yet more buttresses were added, resulting in the majority of the dam face being covered in brickwork.

In best Time Team tradition, the most exciting event occurred on the afternoon of the penultimate day when diggers were investigating an area of odd soil colouring. The resulting pit contained a mixture of what appeared to be metal spikes piercing substantial timbers. Could this be part of the slitting mill machinery? The pit lay below the floor of the corn mill and could have offered a convenient place to dispose of unwanted materials during the conversion process. The plan was to excavate further on the last day but unfortunately this was foiled by the weather. Persistent rain on a site of predominantly clay soils make for difficult and dangerous conditions underfoot and so work was restricted to recording the findings, and the pit was filled in to preserve the artefacts for future investigation.

This was a most enjoyable project, everyone worked well together and a lot more is now known about the site. However, as always, whilst some questions have been answered and a few theories quietly abandoned a new lot of questions have materialised and new theories are called for. When funding becomes available and work recommences, there will be no shortage of volunteers to delve again into the past of this historic site.

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