106 Proceedings of the Royal Irish Academy. 
parts is constantly blown about by the wind; but when it falls on 
places having a grassy covering, some of it remains and is not blown 
off again, owing to the shelter afforded to it by the blades of grass. 
As the grass grows longer, so as to be able to afford more protection, 
more sand will be retained, and therefore the protected parts become 
gradually higher, while the hollows, which are unprotected, tend to 
become lower. In this way the black layer, which is the old surface 
on which the ancient inhabitants lived, became slowly and gradually 
covered over with a great thickness of sand; but in many places the’ 
protecting sward has got broken, and the wind speedily carried away 
the sand, forming large hollows. There are various ways by which 
the protection of grass may be broken through, such as the burrowing 
of rabbits, but the practice of drawing sand for agricultural purposes, 
which has lately come much into use, has been a certain cause of 
openings on which the wind could act. Part of the Sandhills near 
Ballintoy, where I obtained many flint implements, was, within the 
memory of an old inhabitant of the district, covered with a thick sward 
of grass, but when an opening was made, the wind soon carried off a 
great thickness of sand, laying bare the old surface with all its trea- 
sure of wrought flints and accompanying remains. This old surface 
layer, in all the places I have found it to exist, withstands the 
denuding action of the wind for a long time, and the objects it con- 
tains are only gradually uncovered; but at Dundrum, as in other 
places, it has been cut through in many parts. In such cases the 
lighter material has all been carried away by the wind, and the various 
dressed flints and flakes which it contamed are left exposed on the 
sand. Frequently, when we mount a hill, we will see lying in the 
hollow below or on the slope of an opposite hill innumerable white 
objects shining in the sun. These are the flints and bones which have 
dropped out of the layer, and it produces a most agreeable sensation 
when one comes on such a place for the first time and sees all the lost 
objects which the old surface layer contained spread out before him. 
Where the flints have been left bare, by the dark layer being carried 
away, | have observed that they are not strewn continuously over the 
surface, but are rather confined to certain spots. You may meet with 
a considerable number, all collected within the radius of a few yards, 
thicker towards the centre and gradually thinning as you approach the 
circumference, till at last none at all are to be found. Then, ata 
short distance, we may find another spot where they will be met with 
in abundance as before. We sometimes find a few boulders in the 
centre of these spots, which I believe have been used as hearth-stones, 
and therefore I conclude that those places where we find the accumu- 
lation of flints are sites of dwelling-places, and that the manufacture 
of flint implements was carried on in and around them. At Ballintoy, 
foundations in stonework of such dwelling-places are visible, and the 
outline is in some cases still perfect. 
I have frequently called the black layer the implement-bearing 
layer, because it is only in it we find implements of flint, except in 
