Mr. Osmond Fisher, in an article in the January number of this Magazine, entitled “Convection Currents in the Earth's Interior”, speaks of my views in a way that may give a false conception of what they are on the subject of overthrusts. He appears (inadvertently, no doubt) to credit me with a disbelief in the thrust-planes occurring in the North-West Highlands. I may say at once that I am one of those who admire the way in which a band of enthusiastic geologists have worked out the structure of this most difficult tract of country, and thoroughly believe in the correctness of their conclusions. The principal object of my little paper in the November number of this Magazine (1908) was to caution geologists not to push their new-born views too far in trying to account for structural difficulties by overthrusts. It must be remembered that the Moine thrust-plane has been proved to no more than 10 miles overlap, but may, of course, be much more. Incidentally, I thought the paper likely to elicit a correspondence helping the interpretation of the phenomena of overthrusts.