In one sense this is a trivial plan. It was evidently created to record a small land exchange in Bolton between two large proprietors: William Henry Rawson and Miss Sarah Jowett of the Clockhouse Estate. I can’t see an internal date but an unknown predecessor of mine has decided it was 1848. I think that, in fact, it is somewhat earlier. A clue is that at the top of the map is hand-written the name George Baron, who succeeded to the ownership of the Clockhouse Estate as early as 1840, the year that Sarah Jowett died. I’m not sure about William Henry Rawson. His surname was reasonably common; Benjamin Rawson was Lord of the Manor of Bradford and there were also important Rawsons in Halifax who founded a bank.

As well as being dateable the plan includes a definite place, Delph Hill in Bolton. A delph is an alternative, and widely used local name, for a stone quarry. Many Heaton and Bolton quarries exploited Elland Flags sandstone which is found in the Lower Coal Measures just below the Better Bed Coal seam. About 20 yards below Elland Flags is the 80-Yard (or Gaisby) Rock which forms, for example, the top of Baildon Hill and was mined at Bolton Woods and Spinkwell Quarries. About 20 yards under this is the 48 Yard Rock which forms a platform on Baildon Hill. Another 20 yards brings us to the 36 Yard Coal (Band Coal) seam below which is the 36 Yard (Stanningley) sandstone. All these stones have been quarried in the north Bradford area. I think it is fair to say that large quarries with an export trade in stone (like Spinkwell) were unusual. Most were small ‘neighbourhood quarries’ supplying material for local roads, walls, causeways, and housing.

The next detail is from a geology map based on the first OS map of the area. Delf Hill is in the bottom right corner of the plan and is definitely on the Gaisby Rock. White geological faults run across the whole area.

The topography around Delph Hill is shown well in this detail. I’ve chosen this orientation to fit with subsequent OS maps, the earliest of which was probably surveyed a decade later.

The final map detail is from that first OS map (1852). The Trap Sike was the border between Wrose and Bolton. South of this is a coal mine and several quarries. Delph Hill now actually has a delph, although there must have been earlier quarrying to provide the place name. If our initial map is accurate there has been both demolition and house construction in the interval. The field boundaries don’t match perfectly, but I don’t that there is much doubt that the location is correct.