§ 1. Introduction. At the end of a paper forwarded to the Society in December 1859, and printed in the 16th volume of the Quarterly Journal, I gave a concise outline of what seemed to me to have been the geological history of Scotland since the commencement of the glacial period. The following pages are devoted to a further illustration of this subject. The facts on which I rest my conclusions are derived from the midland region of Scotland, chiefly from the part lying between the Moray Firth and the Firth of Forth. This district seems to me to contain remarkably good evidence of the changes that have taken place, and these changes, I believe, have been general over the greater part of Britain. § 2. Preglacial Traces. The absence of the later Tertiary strata in Scotland leaves us in the dark as to the state of things that ushered in the glacial period in that country. There are, however, on the eastern coast of Aberdeenshire, in the parishes of Slains and Cruden, some thick masses of sand and gravel which appear to be of Tertiary age, and are probably equivalent to the Red Crag of England. These beds, in some places, contain remains of shells evidently belonging to a considerable number of species, but so broken and worn that in the great majority of cases it is impossible to arrive at a satisfactory determination of their specific character. Nevertheless I have got enough now collected to enable me to