GLASGOW ARCHAEOLOGICAL SOCIETY.
explained. Was the white clayey substance found at Croy an
integral part of the soil composing the sod1? To put it otherwise,
was it simply a sod that happened to be of clay,'2 or was the clay
introduced as in some way increasing the adhesiveness of the
structure ? What is the meaning of the single thick dark line found
occasionally extending near the ground outside the kerbs outward
from the vallum for several feet along the berm ? Was it the
original surface line of the ground ? These questions must
stand over unsolved by us. Some other matters there are
touching the dark lines, especially the occasional concave
curvature of their direction and their frequent slight protraction
beyond the line of the kerbs, but these will be more appropriately
dealt with under a subsequent head. There is nothing in any of
these respects which, in our judgment, seriously affects the conclu-
sions to be drawn from so many facts fitting so well to the
cespiticious theory.3 That hypothesis we have had little
difficulty in accepting. We believe that the Roman4 spoke
by the card when he called our wall a mv/rus cespiticius.
Further, we consider that the indications are distinctly opposed
to any possibility of the sod work having been confined to an
exterior revetment. To all appearance the structure has been
homogeneous. We do not think it can have been composed
of promiscuous earth in the centre and faced with turf—it
was, we think, of turf throughout, excepting, of course, its
base of stone. We cannot at all reconcile the phenomena
with any theory of the work having been constructed of earth
in layers, alternating with fascines or cervoli. In our judgment
the sod must have been the unit of construction. There are
difficulties ; but the theory carries in itself a reasonable answer
to them all.
1 Reasons advanced for answering this question in the affirmative are (1) that the
dark lines run through the substance ; and (2) that in the case of section Croy
No. II, the whitish strip of clayey soil is 13 inches broad, which would not be far
off the length of a sod.
2 One point is happily free from doubt. Professor John Young, M.D., Glasgow
University, who has kindly tested two specimens, states positively that they are
ordinary clays procurable at the surface, where they would naturally have a turf
3 See separate note by Mr. Haverfield, "A Turf Wall in North England,"
forming Appendix III.
4 Julius Capitolinus. See quotation, supra, p. 4.