I.—On the Origin and Mode of Formation of the Concretions in the Magnesian Limestones of Durham

Abstract

In 1826, 27, and 28, Prof. Sedgwick contributed to the Geological Society of London his classical papers on the Magnesian Limestone of the East of England, in which he describes in detail the concretionary structures which occur in many of the beds of this formation in Durham.Although he describes these concretions in minute detail, he says but little as to their probable origin, but it is clear that he regarded them as composed of carbonate of lime derived from the beds in which they occur, when he says—“The particles (of lime), after deposition, appear to have run into lumps and masses more or less crystalline, rejecting great portions of the earthy residuum.” Since Prof. Sedgwick's papers little seems to have been contributed to the subject of the mode of formation of these concretions.