The year is established by the relationship between this letter and the letter from T. F. Jamieson, 24 March 1862 (Correspondence vol. 10).

Charles Lyell. In his letter of 24 March 1862, Jamieson had offered confirmatory evidence for his view that the parallel roads of Glen Roy (three terraces that run parallel to one another along the sides of Glen Roy in Lochaber, Scotland), were formed when ice trapped a series of lakes in the glen, and that the ‘roads’ represented the shorelines of three of these former lakes. CD had argued that the roads were the remains of beaches formed by the sea as the landmass of Scotland rose in graduated steps. See CD’s 1839 paper, ‘Parallel roads of Glen Roy’, and Rudwick 1974.