Notes on the reconstruction of Scarborough Keep

 On Castle Hill at Scarborough lie the ruins of a Norman Keep and various walls, together with a hall and residence built by King John (forget what ever you have heard about John, the story is much more complicated).  The Keep is built in a different position to the ill-fated Roman Signal Tower - and the positioning of the Keep sends a couple of clear messages about what this fortification was about, and echoes some of the earlier defeats at this location. 

Surprisingly, until recently, the Keep, even in ruinous form, was still protected by Defense Regulations that prohibited  measuring the height or other features of the Keep -  Scarborough had been the subject of a wartime bombing attack. A model of the Keep was one of the first 3D assets we built when starting the task of rebuilding the medieval town of Scarborough (details are elsewhere in this blog - but note that basic information about the dimensions of the Keep were hard to come by). More recently, a friend visited the town and took thousands of images of the bits that still stick out of the ground, like the ruins of the keep and the other structures on Castle Hill. Wandering around the 3D model taught us a couple of valuable lessons denied modern visitors to the site. Firstly, the keepers residence had access to the chapel's roof and interesting views of the fortification, town and harbor. The upper fortifications are focused on the North Sands and the town, but have good views of the western hinterland. In the literature, there are hints of a second southern tower at the end of the wall along the hill, that commanded a view over the port and South Sands - a later tower in this location is called Cocks Tower, the first part of the town to catch the morning sun (and probably the first to fall into the sea as erosion strikes the hill). Is it possible that the town's seal records an echo of this missing bit of the fortifications?

Initially, we wondered whether the ashlar facing stones of the Keep were taken from the Roman Signal Tower, there is strong evidence for the reuse of Roman materials in other medieval structures at Scarborough Castle. Excavations in 1973 identified Roman stylobate blocks (stone bases for timber posts) reused in the 12th-century Great Hall. 

However, while it is probable that the Roman sites nearby were robbed for rubble, as the Keep was a high-prestige royal project for Henry II, its exterior was probably composed of high-quality, newly quarried red sandstone ashlar. While some internal core material might have come from older site ruins, the distinctive, regular facing stones you noticed are typical of the 12th-century royal masonry style. Rather than reusing facing stone from the Roman sites, the ashlar blocks for Scarborough Keep were sourced from local Jurassic sandstone and limestone quarries, primarily utilizing the geological formations found on and around the Scarborough headland itself. Maybe even working in the original Roman quarry pits used to build the Signal Towers and other coastal buildings (as at Eastfield).

Much of the dark red-brown and honey-colored stone is Lower Calcareous Grit or Osgodby Formation sandstone. These formations were historically worked along the Scarborough coastline. Hard stone from White Nab (a headland just south of Scarborough) was used for significant maritime and coastal construction in the area. High-quality, fine-grained sandstone known as Hackness Rock was quarried nearby and used for many prominent buildings in Scarborough, including the 12th-century church and later historic monuments. The harder, "honey-colored" stone seen in parts of the headland is Corallian Group limestone and sandstone, which provided a durable material for the exterior shell. 

For a massive structure like the Keep, medieval builders would have used the Inner Bailey ditch and the ditch at the foot of the hill as a source for the rougher "core" stones, while finer ashlar was brought from more specialized nearby coastal quarries by barge along the coast or by oxen-drawn sleds for shorter distances from local inland quarries.

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This is all a bit disappointing - the beautifully eroded stone we can still see on the ruined castle (see  first immediately shot above) is an artifact of time (and gunpowder). Back in the medieval period, the exterior of Scarborough Keep was characterized by smooth-cut, sharp-edged ashlar blocks. And here is an unexpected kicker - it was likely protected by a layer of limewash or thin lime render. The Keep was a White Castle. The limewash waterproofed the porous sandstone and protected it from the harsh, salt-laden sea air (the "White Tower" in London is the most famous example of this practice). Like the town below it, the castle was constantly being repainted white.

So, in the 12th and 13th centuries, it would have presented as a smooth monolith, standing as a sharp-edged symbol of royal power. Or that is the theory. Elsewhere, we find signs that the castle had been let run down a bit during Henry III's time. Accordingly, we have opted for a slightly flawed monolith - instead of a thick lime slurry, we have let the underlying stone work show through. While cantilevered timber hoardings would have been a desirable feature given the disruptions of 1263-4, we have opted for a mix of hoarding types to reflect confusion and lack of workers to defend the Keep. 

To compensate, we have fitted out the keepers rooms with the best gear we could find.