OR/15/053 Skipness Castle

From Earthwise
Jump to navigation Jump to search
Everett, P A, Gillespie, M R and Tracey, E A. 2015. Provenance of building stones in four 'galley castles' in Argyll. British Geological Survey Internal Report, OR/15/053.

Skipness Castle is located a short distance inland from the shore of Skipness Bay, on the east coast of Kintyre. The site would have provided the castle occupants with an open view across Kilbrannan Sound to Arran.

Skipness Castle is comprised of a high Curtain Wall that encloses two earlier structures: the Hall House, adjacent to the North Curtain Wall, and Chapel, adjacent to the South Curtain Wall. Three rectangular Towers are located at the West Curtain Wall, the Northeast Corner and the Southeast Corner. The East Range was partially demolished and reconstructed as a three-storey Tower House with Parapet Walk in the northeast corner. Entrance is gained through the Gatehouse in the west section of the South Curtain Wall. Much has been altered and demolished, leaving the Curtain Walls, Towers, Hall House and Tower House. A timeline of construction and alterations for Skipness Castle is presented in Table 3.

Table 3 Timeline of construction and alterations in Skipness Castle
Information from RCAHMS (1971) [1]
Date Action Location or masonry element
Early- to Mid-13th C Construction Hall House, Chapel
Early-14th C Construction Curtain Walls
Early-14th C Remodelled Chapel
Late-13th to Early-14th C Construction Northeast Corner Tower, Southeast Corner Tower, West Tower
Late-13th to Early-14th C Construction Entrance (South Wall)
Late-13th to Early-14th C Construction South and East Ranges
Early-16th C Reconstruction Northern section of East Range raised 3 storeys to form Tower House
Early-16th C Construction Parapet Walk adjacent to Tower House
Late-16th C Reconstruction Tower House and Parapet Walk
Late-16th C Demolition Southern section of East Range
Late-17th C Abandoned All
Late-18th C Conversion Farmstead
Late-18th C Demolition Early inner courtyard buildings (except Tower House)
Late-18th C Construction Lean-to buildings and offices (for use as Farmstead)
1898 Demolition Lean-to buildings and offices
1898 Repairs All
Figure 10 Plans for Skipness Castle with periods of construction and alteration. Source: RCAHMS (1971) [1]; pages 166–7.

Building stones

Walling stone

Virtually all of the walling masonry throughout all stages of construction is random rubble (Figure 11a), which consists almost entirely of variably foliated greenish-grey metasedimentary rock. In detail the rock consists of thinly interbedded layers of sandstone and mudstone with veins and blobs of quartz. Flakes of the platy mineral mica, which is produced during metamorphism, are aligned parallel to the metamorphic foliation plane (this is known as a schistose fabric).

Figure 11 Decorative stones in Skipness Castle.
a – pink sandstone window dressings and a doorway lintel formed of a tabular block of foliated metasedimentary rock. b – pink sandstone quoins at the SE corner of Skipness Castle. c – white sandstone structural corbels and pink sandstone decorative corbels at top floor level, S elevation of the Tower. d – worn paving flags of pink to buff sandstone on the N side of the Tower parapet. e – pink and white sandstone dressings around a doorway in the Curtain Wall, E elevation.

The blocks have been shaped by splitting the stone along the foliation plane, which is a natural line of weakness. This has resulted in broadly tabular blocks, typically placed horizontally in the wall. The rock is typical of the bedrock formation that surrounds Skipness Castle, the Beinn Bheula Schist Formation, and has almost certainly been extracted locally, probably from one or more small quarries and from loose material in superficial deposits.

The same metasedimentary rock has been used in all stages of construction, indicating the stone was being sourced locally for building throughout the early 13th century until the late 16th century.

Rounded blocks of granite have been used in some parts of the walling; these would have been sourced locally from superficial deposits.

Decorative stone

Foliated metasedimentary rock

Relatively large, tabular blocks of the local bedrock have been used to form lintels for doors and windows (Figure 11a), and smaller blocks have been used to form archways. This stone is the same as the stone forming most of the walling, and would have been sourced from the Beinn Bheula Schist Formation. The most strongly foliated rock appears to have been used to form tabular blocks for load bearing masonry spans.

Pink sandstone

Most of the decorative stone in Skipness Castle is medium-grained pink sandstone, which displays prominent parallel and cross-bedding, and is commonly cut by numerous small geological faults of a type that typically forms in porous sandstone (these are known as granulation seams, and they tend to weather proud of the surrounding stone because they consist of durable quartz). This sandstone has been used for quoins and dressings for archways, windows and doors (Figure 11a, b). It has been used to form two courses near the base of the curtain wall, indicating that it was being used in the castle from at least the early 14th century (when the curtain wall was erected to enclose the earlier hall house and chapel); however, these courses are not featured in the sections of the curtain wall that were incorporated from these older buildings. The same pink sandstone has also been used to form the decorative corbels and parapet slabs at the top of the Tower House (Figure 11c, d), indicating that the same sandstone has been used throughout all stages of building and alterations (though it is not clear whether new supplies were obtained or existing stone was recycled).

The pink sandstone is closely similar to BGS samples from Corrie quarry on Arran (see Sandstones; Figure 7). However, Permian sandstone of similar character crops out in other parts of Arran, and the stone may have come from another quarry in the same geological formation. The closest outcrop of Permian sandstone to Skipness castle is at Cock of Arran.

White sandstone

A small proportion of the sandstone blocks in Skipness Castle are white sandstone. The stone displays parallel and cross bedding, and some blocks are cut by granulation seams. This sandstone has been used in dressings to a side door by the postern, and forms structural corbels on the turrets of the Tower House. These elements are additions dating from the early 16th century; the white sandstone it is not featured in earlier phases of building (Figure 11c, e).

Although it is white rather than pink, this sandstone is closely similar in many respects — including the bedding character and presence of granulation seams — to the pink sandstone used elsewhere in Skipness Castle, raising the possibility that both are of similar age and from a similar location. A thin section examination of both would be required to test this hypothesis. Based on the available information, the white sandstone in Skipness Castle is likely to have been sourced from Permian or Triassic strata on Arran, possibly near to the site where the pink sandstone was extracted.

References

  1. 1.0 1.1 RCAHMS. 1971. Argyll: an inventory of the ancient monuments, Vol. 1 Kintyre. The University Press: Glasgow