Geograph - photograph every grid square

As shown here NU1835 : Cliffs on the south side of Bamburgh Castle the dark grey, blocky rock on which the castle stands is quartz dolerite, part of the Whin Sill. It was intruded as molten rock at a high temperature between the layers of sedimentary rocks, taking on its distinctive columnar, vertically-jointed form as it cooled and crystalised. The dolerite layer on which the castle stands is about 10m thick as it is along Hadrian's Wall. Below the dolerite, at the level of the war memorial, the pinkish coloured rocks are sandstone laid down in extensive horizontal layers. Between these layers there are fine striations cross-cutting at different angles. These are sandstones laid down by ancient rivers, with the fine striations - called cross-bedding - a feature of sediments laid down as ripples.