Mexborough & Swinton Times – Friday 05 September 1879
Excursion To Conisborough.
On Saturday afternoon a party of the University Students’ Association visited this pretty village for the purpose of exploring the permian rocks so profusely found in its immediate neighbourhood.
The first object of interest was the upper coal measures, found in the neighbourhood of the Doncaster-rd. This spot is rendered more interesting as it is the only place in Yorkshire where the upper coal is found. The whole of the formation, with this exception, has been removed by denudation and erosion probably before the deposition of the red marl resting unconformably upon it.
The keep of the old castle was next visited, a portion of the party ascending to the summit and admiring the beauty of the panorama spread beneath them.
After enjoying a hearty tea the business of the association was proceeded with.
The party inspected a quarry being worked in the dolomitic limestone, capped by the red marl (a distinguishing feature of this formation). The idea of the magnesian limestone being the result of an inland sea was discussed, and several pieces of the rock were secured for future inspection and analysis. This sea must have been filled with animals of a low type of organisation, portions of the rock being literally composed of “orbiculina” and other minute crustaceans belonging to the order ostracoda.
Some specimens were found in which the shells of the lamellibranchiata (arca antiqua?) were abundant. The position occupied by the remains shows that they were slowly deposited on a sea bottom undisturbed by currents. The party returned home much gratified and instructed by their excursion.