On the orientation of boulders

Abstract

It is a common observation with regard to the scattered boulders and perched blocks, which are perhaps the most striking relics of a past ice-age in our country, that there is a general correspondence between the position of their longer axis and the direction in which they have been transported. When examined, it is usually found also that the striations upon them run length-ways, and correspond in direction with those on the solid rock beneath. From the Reports, for England, of the Boulder Committee of the British Association, and for Scotland, of the Boulder Committee of the Royal Society of Edinburgh, as well as from innumerable papers by private observers, an immense number of instances might be cited to show that the coincidence of the longer axis with the direction of movement is a very general characteristic of these masses. Frequently, also, it has been observed the sharper or lighter end of the boulder points in the direction towards which it was being moved, and the broader or heavier end in that from which it had come, showing that it was being carried or pushed forward in the position of least resistance. These facts are generally known and accepted, and the conclusion drawn from them in favour of the boulders having been transported by land ice, and not by floating ice in any form, may also now be taken as one of the commonplaces of glacial geology. But there is one point obviously bearing on this conclusion which seems not