|BGS Image ID: P002240|
Concretionary balls with calcareous cement in a sandstone of Ballagan Formation, Inverclyde Group (formerly Calciferous Sandstone Measures). This is an exceptionally large concretion which forms when minerals (here calcite but can also be silica) migrate towards a centre and concentrate into a discrete spherical body. Carboniferous strata in the Cockburnspath to Dunbar area rest on Silurian rocks of the Southern Uplands terrane and form the landward margin of a large basin which extends eastwards into the North Sea. When rocks are deformed, the concretions also deform, commonly into ellipsoids. By making an assumption about their original shape, the proportions of the deformed concretions can be used as a measure of the amount of deformation.
The Ballagan Beds is the same formation the nearby TW:eed Project were drilling while looking for 'Romers Gap'. It was a scientific research project undertaken this year to study fossils and environments from the Early Carboniferous Tournaisian Stage, roughly 350 million years ago.
BGS Old photograph number: C02038. Date of photograph: 1914.