Notes on the Sutherland Gold-Field

Abstract

I ntroduction . T he district of Sutherland in which gold has been recently discovered and worked, in certain waterworn materials and gravelly detritus which cover the crystalline Lower Silurian rocks in several depressions at and near Kildonnan in Sutherland, is the eastern extremity of a region which I have personally explored at intervals for the last forty-three years. It was, however, only in the year 1858 that I fully satisfied myself as to the relative ages and order of superposition and character of all the various rock-formations which occur between the western and eastern coasts of Sutherland and Ross. It was then that for the first time I was enabled to show distinctly ascending order from the fundamental gneiss or Laurentian rocks of the northern highlands, through great masses of sandstone and conglomerate of Cambrian age, upwards through overlying quartz-rocks and limestones, which, thanks to the fossil discoveries of my friend Mr. C. Peach, were proved to be of Lower-Silurian age. It was also shown that these Lower Silurian rocks, in their extension eastwards and dipping slightly to the east south-east, became more and more crystalline as they trended in that direction, and that when perforated by bosses of eruptive rocks, chiefly granite, they rolled over in undulations in a highly metamorphosed condition, until they were surmounted unconformably by the Old Red Sandstone and younger deposits of the eastern coast. In order to be able to reason upon the probable sources of the gold detritus which occurs in the gullies (valleys) of