Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/123

Rh Specimens illustrative of the manufacture of gun-flints explain most fully the force of the arguments brought forward to prove the mechanical origin of these " drift" flint flakes.

These worked flint flakes occur in two very distinct formations — the most ancient that of the marine drift-sand and gravel which skirts the shores of Belfast and Larne Loughs, in the co. Antrim, and the coast from Holywood to Donaghader, in the co. Down — its maximum elevation being about 20 feet above the level of high water. All the flakes from this deposit are of the ruder forms, and their surfaces are more or less oxidized or rendered white : and though they are imbedded in what was well-washed or rolled sea-drift, the chippings round their sides and angles are remarkably sharp — thus proving that they did not suffer much attrition after their submergence, and before the elevation of the marine-drift to its present subaerial position.

The more recent flakes are found in the subsoil clay, at all elevations up to 600 feet or so, on the northern slopes of the Cave Hill at Belfast, the commons of Carrickfergus, and the lofty ground around Larne Lough, including that of Island Magee.

These flint flakes sometimes occur in groups, and so abundantly that hundreds of them can be collected over a surface of 50 square yards, and they are all more or less characterized by a comparatively fresh look ; but they all possess that porcellanous glaze which time alone can give to the surface of a fractured flint.

At one locality on the east coast of Island Magee, at the south end of " the Jobbins," I found a hoard of these subsoil flakes, and on the west shore of Larne Lough, at Ballybig, a similar collection of the older variety of these implements in the marine-drift. Here they were accompanied by large irregularly shaped lumps of flint, on one of the edges of which was preserved the original rounded surface of the nodule, evidently thus left to fit them to the hand, and thus allow of their being used as hammers to fabricate the required flake of flint.

In some rare instances the subsoil flakes, when originally of the arrow-headed type, present near the bulb of concussion (which then becomes the base of the implement) the flint- chipping necessary to form the wing of a perfect arrow- or javelin-head. Flakes of this variety are most usually found in the interior of the co. Antrim, as at Toome Bridge and near Moira.

The Rev. Dr. M'llwaine, of Belfast, has kindly allowed me to make some sketches from flint flakes of this character in his collection ; and I now beg to present them to the portfolio of the Geological Society, to aid in making as complete as possible the small collection of flint flakes which accompany these remarks *. In some rare instances deep side-notches are observed on the more ancient oxidized flakes from the marine drift ; but their position is variable.

So far as our present information leads us, I believe we can arrive at the following conclusions with reference to the origin and mode of occurrence of these worked flint flakes : —

During the formation of our present raised sea-beaches, the in-


 * Deposited in the Society's Collection.

VOL. XXV. PART I. E