Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/85

 interstices of the basalt I have noticed ironclay of a brick-red colour, and at Glenwhelt Mr. Fryer detected small veins of dark leek-green talc in thin leaves mixed with iron pyrites and calcareous spar. This fossil on being exposed to the action of the blow-pipe divided into extremely thin folia, and changed from green to copper colour with the addition of borax it melted into a greenish black bead.

These overlying masses of basalt appear also at Barwesford on the North Tyne, and are continued to the vicinity of Thockrington and Bavington, to Kirk Welphington, and thence in a north-easterly direction as far as Causway-park, north of Morpeth.

Proceeding further to the north, basaltic eminences form a striking feature in the country between Alnwick and Berwick. These eminences have frequently been chosen for the sites of castles, as at Dunstanborough, Bamborough, and Holy Island. The hills near Belford, the rocks called the Staples which emerge from the sea at the distance of six miles east of Bamborough, and the Fern Islands situated half way between the Staples and the shore, are likewise composed of basalt.

At Craster near Howick, where the millstone grit is also found, basalt was formerly quarried and shipped to London for paving-stones. Craster house is fronted with this rock.

In the north-eastern face of the cliff, on which the ancient fortress of Dunstanborough stands, the following series of strata is exposed to view: