Corse Croft, Loanend

NJ54SE 19 5577 4422

(Location cited as NJ 5577 4422). Corse Croft, Huntly ph. Analysis of thatched roof. Field recording and detailed laboratory analysis of the roof was undertaken as part of an ongoing archaeological analysis of Scottish thatched roofs. The building, now used as a lambing shed but originally a dwelling, retains degraded areas of the thatch under sheet metal. It remains undated at present but was found to consist of a number of courses of oat straw held in position by layers of clay up to 3cm thick. Courses of broom were noted from both the ridge and the eaves above the door.

Sponsor: Historic Scotland

T G Holden 1996.

Corse Croft comprises a stone-built house and several outbuildings. During renovation of one of the latter, several of the roof-timbers were replaced, a turf gable-wall was repaired and the eastern part of the corrugated iron roof was lifted to reveal that remnants of the original thatched roof remained in situ. Oral tradition and the presence of a gable-end fireplace indicate that the building was originally a dwelling, although latterly used for storage and lambing. The 1st edition of the OS 1:10,560 map indicates buildings on the sites now occupied by the main house, the building under investigation, and another (now used for storage) on the S side.

The main constituents of the thatch were found to be clay and straw, much of the latter having deteriorated through erosion, disturbance and rodent activity. The thatch was missing from along the apex, much of the loose material having fallen or been blown down the pitch to accumulate as fine organic detritus at the eaves.

The structure of the roof was found to comprise a series of rough-hewn timber slabs (about 15xcm thick and positioned about 4cm apart) which were laid horizontally across the pitch to act as a sarking layer. The main body of the thatch was laid directly onto these and comprised overlapping courses of cereal straw held in position by layers of clay 2-3cm deep to form a coat 50-60cm wide running from gable to gable. The incorporation of stones measuring up to 7cm across indicates that the clay preparation technique was not concerned with producing a uniform texture.

Samples were taken from points above the door and just below the apex but without the loose overburden found lower down. Oat straw with a pinkish hue was recognised and broom had also evidently been used; the stems had been sharpened ibn cutting and pointed towards the apex. Three sharpened pegs (measuring 30-45cm in length and 2-4cm in diameter) had been pushed horizontally into the thatch above the door; the largest of these retained a short length of coir rope which had been wound around the external end. Other materials (including rushes, grass and broom) had been used in the lower portions of the roof.

Block 3 was dissected under laboratory conditions and found to comprise remnants of a cereal straw layer and loose twigs of broom overlying an eroded clay layer which was 2-3cm deep and contained occasunal small stones. Beneath the straw layer, there was a sequence of clay layers holding down layers of oat straw laid in directional fashion. The presence of significant quantities of leafy material within the straw layer suggests that these were not stripped. The clay was apparently laid in a plastic fashion and had been pushed onto the straw layers to retain individual straws.

The structure of the roof was such that, with the exception of minor repairs, all the elements above the sarking layer probably relate to one thatching, with no evidence for a cumulative process.

NMRS, MS/899/16.

Detailed analysis of six samples from the turf gable was carried out by Headland Archaeology Ltd with the objectives of identifying the source of the turf and investigating the tools and techniques used in their cutting. They were divided into three pedological groups:

Type 1 (turves A, B and E). The upper horizons of a peaty/humic gley intergrade soil, comprising grassy vegetation over a dark grey-brown humicx/peaty A horizon (7-9cm deep) which overlies up to 15cm of grey sandy Bg horizon.

Type 2 (turf F). A sub-surface horizon of a gleyed saoil profile. It comprises up to 9cm of yellow brown sandy Bg horizon. In the absence of vegetation or horizon boundaries, the orientation of the block is not known. The turf has a 1-2cm thick layer on one surface which is rich in organic components (roots and stems) but does not appear to be a natural soil horizon.

Type 3 (turves C and D). The upper horizons of a peaty gley or podzol. It comprises heathy vegetation over an organic litter layer (1-2cm deep) which overlies a dark grey brown Ah horizon (1-2cm deep) which grades into a sandy mineral Ea or Eag horizon at least 6cm deep.

Lithological analysis indicated that metamorphic quartz was dominant or common in all three groups, an alluvial souce being suggested for types 1 and 2, and a source in glacial till for type 3.

Morphologically, the turves were dividied into:

-regular parallelograms, turves A, B and E. All of Type 1 soil, and were typically blocks measuring 16-18cm wide by 8-12cm deep and up to 22cm deep,

-a rounded square turf (turf C) measuring about 17cm square by 5cm thick, and

-more or less regular cubic blocks (turves D and F) with dimensions of about 8-12cm.

Botanical analysis generally revealed a variety of moss species indicative of a heathland environment on acid soils. Degraded grass/sedge/rush remains were also noted.

NMRS, MS/899/20.