The actual structures of Langbank and Dumbuck, then, are confessedly
ancient remains; they are _not_ of the nineteenth century; they are
"unique" in our knowledge, and we ask, what was the purpose of their
constructors, and what is their approximate date?
Dr. Munro quotes and discusses {43} a theory, or a tentative guess of Dr.
David Murray. That scholar writes "River cairns are commonly built on
piled platforms, _and my doubt is_ whether this is not the nature of the
structure in question" (Dumbuck). A river cairn is a solid pile of
stonework, with, perhaps, a pole in the centre. At Dumbuck there is the
central "well" of six feet in diameter. Dr. Murray says that a pole
"carried down to the bottom would probably be sunk in the clay, which
would produce a hole, or well-like cavity similar to that of the Dumbuck
structure." {44}
It is not stated that the poles of river cairns usually demand
accommodation to the extent of six feet of diameter, in the centre of the
solid mass of stones, and, as the Langbank site has no central well, the
tentative conjecture that it was a river cairn is not put forward. Dr.
Murray suggests that the Dumbuck cairn "may have been one of the works of
1556 or 1612," that is, of the modern age of Queen Mary and James VI. The
object of such Corporation cairns "was no doubt to mark the limit of
their jurisdiction, and also to serve as a beacon to vessels coming up
the river."
Now the Corporation, with its jurisdiction and beacons, is purely modern.
In 1758 the Corporation had a "lower cairn, if it did not occupy this
very spot" (Dumbuck) "it stood upon the same line and close to it. There
are, however, no remains of such cairn," says Dr. Murray. He cites no
evidence for the date and expenses of the demolition of the cairn from
any municipal book of accounts.
Now we have to ask (1) Is there any evidence that men in 1556-1758 lived
on the tops of such modern cairns, dating from the reign of Mary Stuart?
(2) If men then lived on the top of a cairn till their food refuse became
"a veritable kitchen midden," as Dr. Munro says, {45} would that refuse
exhibit bones of _Bos Longifrons_; and over ninety bone implements,
sharpened antlers of deer, stone polishers, hammer stones, "a saddle
stone" for corn grinding, and the usual _debris_ of sites of the fifth to
the twelfth centuries? (3) Would such a modern site exhibit these
archaic relics, plus a "Late Celtic" comb and "penannular brooch," and
exhibit not one modern article of metal, or one trace of old clay tobacco
pipes, crockery, or glass?
The answers to these questions are obvious. It is not shown that any men
ever lived on the tops of cairns, and, even if they did so in modern
times (1556-1758) they could not leave abundant relics of the broch and
crannog age (said to be of 400-1100 A.D.), and leave no relics of modern
date. This theory, or suggestion, is therefore demonstrably untenable
and unimaginable.
Dr. Munro, however, "sees nothing against the supposition" that "Dr.
Murray is right," but Dr. Munro's remarks about the hypothesis of modern
cairns, as a theory "against which he sees nothing," have the air of
being an inadvertent _obiter dictum_. For, in his conclusion and summing
up he writes, "We claim to have established that the structures of
Dunbuie, Dumbuck, and Langbank are remains of inhabited sites of the
early-Iron Age, dating to some time between the fifth and twelfth
centuries." {46a} I accept this conclusion, and will say as little as
may be about the theory of a modern _origin_ of the sites, finally
discarded by Dr. Munro. I say "discarded," for his theory is that the
modern corporation utilised an earlier structure as a cairn or beacon, or
boundary mark, which is perfectly possible. But, if this occurred, it
does not affect the question, for this use of the structure has left no
traces of any kind. There are no relics, except relics of the fifth (?)
to twelfth (?) centuries.
In an earlier work by Dr. Munro, _Prehistoric Scotland_ (p. 439),
published in 1899, he observes that we have no evidence as to the when,
or how of the removal of the stones of the hypothetical "Corporation
cairn," or "round tower with very thick walls," {46b} or "watch tower,"
which is supposed to have been erected above the wooden sub-structure at
Dumbuck. He tentatively suggests that the stones may have been used,
perhaps, for the stone causeway now laid along the bank of the recently
made canal, from a point close to the crannog to the railway. No record
is cited. He now offers guesses as to the stones "in the so-called
pavements and causeways." First, the causeways may have probably been
made "during the construction of the tower with its central pole," (here
the cairn is a habitable beacon, habitable on all hypotheses,) or, again,
"perhaps at the time of its demolition" about which demolition we know
nothing, {47a} except that the most of the stones are not now _in situ._
Several authentic stone crannogs in Scotland, as to which we have
information, possessed no central pole, but had a stone causeway, still
extant, leading, _e.g._ from the crannog to the shore of the Ashgrove
loch, "a causeway of rough blocks of sandstone slabs." {47b} If one
stone crannog had a stone causeway, why should this ancient inhabited
cairn or round tower not possess a stone causeway? Though useless at
high water, at low water it would afford better going. In a note to
_Ivanhoe_, and in his Northern tour of 1814, Scott describes a stone
causeway to a broch on an artificial island in Loch Cleik-him-in, near
Lerwick. Now this loch, says Scott, was, at the time when the broch was
inhabited, open to the flow of tide water.
As people certainly did live on these structures of Langbank and Dunbuie
during the broch and crannog age (centuries 5-12) it really matters not
to our purpose _why_ they did so, or _how_ they did so. Let us suppose
that the circular wall of the stone superstructure slanted inwards, as is
not unusual. In that case the habitable area at the top may be reduced
to any extent that is thought probable, with this limitation:--the
habitable space must not be too small for the accommodation of the
persons who filled up the eastern third of an area of from twelve to
fourteen feet in breadth, and in some places a foot in thickness, with a
veritable kitchen-midden, of "broken and partially burned bones of
various animals, shells of edible molluscs, and a quantity of ashes and
charcoal . . . ." {48}
But Dr. Munro assures me that the remains discovered could be deposited
in a few years of regular occupancy by two or three persons.
The structure certainly yielded habitable space enough to accommodate the
persons who, in the fifth to twelfth centuries, left these traces of
their occupancy. Beyond that fact I do not pretend to estimate the
habitable area.
Why did these people live on this structure in the fifth to twelfth
centuries? Almost certainly, not for the purpose of directing the
navigation of the Clyde. At that early date, which I think we may throw
far back in the space of the six centuries of the estimate, or may even
throw further back still, the Clyde was mainly navigated by canoes of two
feet or so in depth, though we ought to have statistics of remains of
larger vessels discovered in the river bed. {49a} I think we may say
that the finances of Glasgow, in St. Kentigern's day, about 570-600 A.D.,
would not be applied to the construction of Dr. Munro's "tower with its
central pole and very thick walls" {49b} erected merely for the purpose
of warning canoes off shoals in the Clyde.
That the purpose of the erection was to direct the navigation of Clyde by
canoes, or by the long vessels of the Viking raiders, appears to me
improbable. I offer, _periculo meo_, a different conjecture, of which I
shall show reason to believe that Dr. Munro may not disapprove.
The number of the dwellers in the structure, and the duration of their
occupancy, does not affect my argument. If two natives, in a very few
years, could deposit the "veritable kitchen midden," with all the sawn
horns, bone implements, and other undisputed relics, we must suppose that
the term of occupancy was very brief, or not continuous, and that the
stone structure "with very thick walls like the brochs" represented
labours which were utilised for a few years, or seldom. My doubt is as
to whether the structure was intended for the benefit of navigators of
the Clyde--in shallow canoes!