A paper on “Glacial Action & its Connection with the Geology of the Neighbourhood” was read by Mr. T.H. Easterfield.
The subject was divided into four parts:- The first part was devoted to a description of the formation of Glaciers & Ice-sheets; the chief conditions necessary to their formation being a high plateau above the line of perpetual snow & plenty of moisture to furnish a continual supply of snow.
In the second part Mr. Easterfield pointed out the effect of an Ice-sheet or a Glacier upon the Physiography & Geology of any Country in which they occurred; showing how they smoothed down irregularities in their path; how they scratched the stones over which they passed or which were frozen into their lower surfaces; how they formed Roche-moutonnée & also probably gave rise to lakes.
He described the deposits which are invariably formed under large ice-sheets & showed by what characters they could be easily recognised. He then drew attention to what would happen when an ice-sheet melted & exhibited a large diagram representing a block of enormous size which has been deposited in its present high position by the action of Ice.
In the third part of the lecture the probable causes of the changes of climate, whereby countries which formerly suffered Glacial conditions are now enjoying temperate climates were discussed. The two most popular theories, those of Sir Charles Lyell & of Herschell & Croll were briefly stated. Lyell’s hypothesis would explain all former glacial conditions by difference in the Geographical distribution of land & sea, whereas Herschell & Croll maintain that they are due to alterations in the earths path round the sun together with other astronomical phenomena.
In the last part of the lecture Mr. Easterfield mentioned the traces of former glacial action that were to be found in the neighbourhood of Doncaster: he showed conclusively that the clay which is worked at Balby & used in the manufacture of Bricks is of glacial pointing out the extent & boundaries of this clay far as they have at present been determined & concluded by exhibiting to the audience a selection of the stones from the Balby Clay most of which were ice-scratched.
The lecture which was listened to with much interest & attention was illustrated by a number of large diagrams kindly lent for the purpose by Prof. Green of Leeds.