xxxvi Obituary Notices of Fellows deceased. 



junction of the quartzite with the Lewisian gneiss, and to the litho- 

 logical zones in the quartzite. This was necessary hecause only the 

 upper part of the quartzite — the "pipe-rock" of Mcol — is exposed 

 in Lapworth's type section at An-t-Sron, on the otlier side of the loch. 

 Our first work in Eriboll was to examine this section. There he 

 demonstrated the normal succession from the pipe-rock of the quartzite, 

 through the " fucoid " beds and the salterella grit, to the limestone, 

 directing our attention to the various zones — seven in all — which he 

 found useful for mapping purposes, and had already described in his 

 paper on ' The Secret of the Highlands.' 



During the remainder of the time we were with him, about two days, 

 he took us rapidly over the ground that he had surveyed in the 

 previous year between Eriboll House and Whiten Head. First he 

 proved to us that the zonal succession which he had established at 

 An-t-Sron was repeated on the opposite or eastern side of the limestone 

 basin, with steep dips and other complications that it would have been 

 very diflicult to unravel without a knowledge of the true sequence. 

 At ArnaboU hill he showed us the Lewisian gneiss, resting on quartzite, 

 called our attention to the abnoruial aspect of both rocks, especially 

 near the junction, and gave us his interpretation of the facts. The 

 gneiss, he said, had been forced westward over the fossiliferous sedi- 

 ments on an overthrust-fault of low hade, and the abnormal aspect 

 of the rocks seen here, and at many other places which we subsequently 

 visited, was due to the fact that they had been crushed and in some 

 cases rolled out by what he called the earth-mill, so as to be almost 

 unrecognisable. He invited me to take specimens and examine them 

 under the microscope, as he had done. Those specimens are now some 

 of my most cherished possessions, for they introduced me to a new 

 petrological world. He suggested that the term " mylonite " would be 

 appropriate for rocks that represented the extreme phase of mechanical 

 metamorphism, and this term, now well estabhshed, he finally adopted. 



Leaving Arnaboll hill we worked northwards towards Whiten Head, 

 and, to remove any doubt that might linger in our minds as to the 

 identity of the " Upper Quartzite " of Murchison with the " Lower 

 Quartzite," he placed me on the latter with instructions to walk along 

 it, making sure that I never left it. He and Blake took up their 

 positions ou the " Upper Quartzite," and moved in a direction roughly 

 parallel to me with the sauie care. Progress was slow, for in such a 

 disturbed area it was necessary to examine every inch of the ground. 

 Finally we met on quartzite, shook hands, and declared that beyond 

 all shadow of doubt the " Upper Quartzite " was merely the " Lower 

 Quartzite " brought up again by the disturbances of which we had 

 already seen such striking evidence. As a further illustration of these 

 disturbances he took me, after Blake had left us, to the shore north 

 of Heilem, and showed me that the salterella grit had there been 



