Budle Bay, on the coast of Northumberland, between Holy Island and Bamburgh, is the estuary of the little river Waren. The rocks of the country belong to the Bernician Series or, in other words, to the alternating grits, limestones, shales, and coals which in northernmost England represent the Carboniferous Limestone Series. The northern shore of the Bay is a broad expanse of sand stretching as far as Fenham Flats and Holy Island, but the southern is rocky though not lofty. The Great Whin Sill (the well-known intrusive sheet of Basalt) is present here, and the late Mr. G. Tate of Alnwick has more than once described it as it occurs here, associated with the beds which form the subject of this note. In 1872 he wrote: “At Budle the basalt is nearly connected with an indurated, jointed, red shale (containing Posidonomya Becheri, etc.), which overlies a limestone; for the basalt is in the hill a little above the schist, and on the sea-shore to the east; so that the jointed and indurated condition of the schist is probably due to the action of the Basalt.”