It was explained that this deposit, known in Scotland as Till or Boulder-Clay, prevails also in Ireland, the Isle of Man, England (north of the Thames), Denmark, and Sweden, though much less abundantly in these last countries. It exists also in the Hudson's Bay districts, and at the south extremity of South America.

It had been a subject of perplexity to geologists ever since attention was drawn to it, fifty years ago, by Sir James Hall of Dunglass, whose papers are in the Transactions of this Society.

About the year 1840 a theory was started to account for the boulder-clay, and other phenomena allowed to be connected with it, by the action of glaciers.