caithness-1911/05_034

Transcription

xxxii -- HISTORICAL MONUMENTS (SCOTLAND) COMMISSION.

make good the lack of natural advantages in position. In numerous
instances where the site was on level ground this was effected either
by excavating a ditch around it, and erecting a rampart or wall on
the top of the scarp, or by building a formidable wall around the
broch at some distance from its base. Examples of the former
method are to be observed in the brochs of Kilmster (No. 507) and
Camster (No. 522); while the latter finds its exposition in the
"Road Broch" at Keiss (No. 517), the Keiss Broch (No. 515),
and the broch at Upper Borgue (No. 206). Where existent, any
low prominence seems to have been selected, and, if necessary,
added to, so as to form a flat-topped mound of such diameter as
would afford room for the tower and leave a space of some 20' or
thereby between the base of the structure and the edge of the
mound. This arrangement was probably adopted to give greater
stability to the broch on its artficial foundation, but it also furnished
a base court into which stock might be driven, thus resembling the
enclosures occasionally to be found in front of the Sutherland brochs.
The average present height of these mounds is about 8'. Against the
scarp in two instances - the broch at Stemster in Reay parish (No.
344) and that at Sibmister in Olrig parish (No. 321), a revetment
was observed, and it is probable that such a stone facing was general.
The remains of a parapet wall or rampart are usually visible around
the edge of the mound, while an encircling ditch, sometimes of con-
siderable dimensions, completed the defences. Over the ditch passed
a roadway on unexcavated ground, giving access to the enceinte.
Good examples of this latter type are "Cnoc Donn" (No. 103), "Carn
na Mairg" (No. 105), and "An Dun" (No. 203). Along the coast
line situations have been selected adjacent to the cliffs, or, as in the
case of castles of later date, on the landward ends of promontories
fortified by a ditch across the neck. Such are the situations of the
brochs of Crosskirk (No. 347) and Borrowston (No. 348) in Reay
parish, Ness (No. 33) and Skirza Head (No. 35) in Canisbay, and
Nybster (No. 518) and "Cairn of Elsay" (No. 521) in Wick parish.
On considering the principal features of the structures themselves
we find that, besides the twenty-four excavated examples, the interior
diameter is revealed in only other six; but, though, as in Sutherland,
this dimension averages about 30', the variation is much greater,
ranging from 22' in the promontory brochs of Ness and Skirza
Head to about 43' in the broch on the cliff at Borrowston. The
existence of two stairs on opposite sides of the court in four of
the excavated brochs - Acharole (No. 466) in Watten Parish, and
Brounaban (No. 511), Keiss (No. 515), and the "Road Broch"
(No. 517) in Wick parish - is a structural feature not observed any-
where in the neightbouring county. In each of the three last
mentioned there was evidence of a second entrance from the out-
side at the foot of one of the stairs. A similar arrangement was
also found in the Ness broch, but unconnected with a stair. Outer
passages leading up to the broch entrance and furnished with door
checks have been exposed in the brochs of Hillhead (No. 520),
Kilmster, and Nybster, while occasionally the wall on either side of
the entrance has been strengthened by additional building on the outer
face, as at the "Cairn of Elsay." Outbuildings forming a network
of irregularly shaped chambers have in several cases been exposed