Sept. 13, 1877] 



NA TURE 



415 



of Hoy, and there, if anywhere, traces of the last glaciers 

 should be found. Two years ago, when engaged with my 

 friend and colleague, Mr. B. N. Peach, in making a care- 

 ful examination of the north end of that interesting island, 

 I found what we had been in search of — a beautiful and 

 complete proof of the unconformability between the Upper 

 Old Red Sandstone and the Caithness flags. So engrossed 

 were we with the magnificence of the natural sections 

 where this structure is displayed, that we had climbed 

 into the mouth of the green corrie below the Coulax 

 Hill before we were aware that we stood upon a glacier- 

 moraine. But from the top of the ridge, and, still better, 

 from the steep grassy slope on the west side, three or 

 four successive horse-shoc-shaped mounds could be seen 

 extending across the valley, and becoming progressively 

 lower and shorter when traced upwards, till the last of 

 them died out at the base of the acclivity behind. Not 

 only were they in external form and arrangement as per- 

 fect examples of moraines as could be desired ; their 

 internal composition bore ample testimony to the same 

 origin. My companion and I found further proof that 

 the other valleys of Hoy had also once nourished their 

 separate glaciers, the most striking evidence being sup- 

 plied by a moraine-mound nearly half a mile long and 

 fifty or sixty feet high, which runs across the mouth cf 

 the glen to the east of Hoy Hill on the north-east side 

 of the island. The angular rubbish of this moraine rests 

 upon a stiff, red, sandy boulder-clay full of striated frag- 

 ments of red sandstone. The hills from which these 

 glaciers descended rise from 1,400 to 1,550 feet above the 

 sea. That so small and so low an island as Hoy should 

 have had its glaciers, creeping probably even down to 

 the sea-level, need not surprise us, when we remember 

 that small ocean-girt groups of mountains, like those of 

 Skyeand Mull, had their glaciers, and that even in Arran, 

 more than three degrees of latitude further south, and 

 from hills little more than 100 feet higher than those of 

 Hoy, glaciers existed on such a scale as to leave behind 

 them the huge moraines of Glen Cloy. 



Mr. Laing refers also to Shetland, and though he states 

 that his acquaintance with that region is not so intimate 

 as his knowledge of Oikney, he believes that as little 

 evidence of glaciation can be found there as among his 

 native islands. In this case, too, I am afraid his state- 

 ments are too absolute. It is now many years since Mr. 

 C. W. Peach chronicled the occurrence of abundant 

 striated rock-surfaces and boulder-clays with striated 

 stones in the Shetland Islands (see " Report" of British 

 Association for 1864, Sections, p. 60). From my own 

 observation also I can speak confidently as to the correct- 

 ness of these determinations. Even on the low and 

 remote westerly islet of Papa Stour Mr. B. N. Peach and 

 myself found boulder clay and many transported blocks 

 of gneiss, schist, and other rocks foreign to the immediate 

 locality, while the prevailing pink porphyry showed glacial 

 stria; running N. 5" W. On the Mainland also, between 

 the head of Bixetter Voe and Walls, we observed some 

 curious mounds which if not true moraines are at least 

 parts of the glacial series. Since our visit my colleague, 

 Mr. John Home, has spent some time in Shetland and 

 has obtained ample evidence of the presence of a sheet 

 of ice over that region (see Nature, vol. xv. p. 139). 

 There can indeed be no doubt that both Shetland and 



Orkney have been severely ice-ground and that the move- 

 ment of the ice has been on the whole along a north-west 

 and south-east line. So far therefore from these islands 

 ofl'ering any exception or difficulty in regard to this 

 geological question they bear their independent and 

 concurrent testimony to the now generally received 

 doctrine. 



1 1. There is, however, one very remarkable feature of 

 Orkney and Shetland to which Mr. Laing has referred, 

 and with regard to which my own observations, so far as 

 they go, thoroughly bear out his statement. I allude to 

 the absence of raised beaches. During the surveys which 

 I have made in conjunction with Mr. B. N. Peach we 

 have continually asked each other what has become of 

 the familiar raised beaches which skirt the Scottish coast- 

 line even as far as the shores of Sutherland. Mr. Home 

 was equally struck by their absence. It is indeed incon- 

 ceivable that if our raised beaches be due to a rise of the 

 ocean level from the accumulation of a polar ice-cap (a 

 doctrine which I for one have never accepted) there could 

 fail to be found some remnants of them among the innu- 

 merable sheltered creeks and bays of these northern 

 islands, in positions where on the near mainland they 

 would assuredly be found. Well-marked raised beaches 

 skirt the north coast of Sutherland within sight of the 

 hills of Orkney. And yet I never observed any trace of 

 a terrace which by possibility could be made to do 

 duty for a raised beach, either in Orkney or in Shetland, 

 and Mr. Laing's much wider accjuaintance with these 

 islands confirms my belief that such terraces probably do 

 not exist in Shetland, if not also in Orkney. But the 

 difliculty of accounting for their absence is not incon- 

 siderable, even if we hold that our raised beaches point 

 to successive elevations of the land. Why should they 

 cease with the northern bays of the mainland of Scot- 

 land ? Can we suppose that the upheaval so marked in 

 Sutherland did not affect Orkney ? 



During a recent visit to Sutherland and Caithness I 

 tried to find some satisfactory solution to these questions . 

 It is important to observe that on the mainland the raised 

 beaches disappear when we pass from the crystalline 

 rocks into the Old Red .Sandstone. Travelling, for example, 

 along the coast-line froin Inverness, by the Beauly, Cro- 

 marty, and Dornoch Firths, we find ourselves, almost 

 without intermission, upon one or other of the level sandy 

 terraces which form so conspicuous a feature of these 

 shores. Even upon the strip of Jurassic rocks the same 

 platform runs on to Helmsdale. But northwards the 

 coast rises in one long line of precipice, from which slice 

 after slice is cut as the lines of joint split open under 

 the influence of air and sea. I have seen no satis- 

 factory raised beach in Caithness. The only places 

 where, from the shape of the coast-line, the existence 

 of such deposits was possible are in Thurso Bay, on the 

 coast between Dunnet and Duncansbay Heads, and in the 

 bays between Freswick and Wick. But even on these more 

 sheltered and less precipitous shores the rock usually 

 stands up in low cliffs and runs out in reefs, or 

 steep banks of boulder-clay rise from the edge of the 

 beach, or ridges of blown sand stretch for some distance 

 inland. Now the rocks of Orkney are identical with 

 those of Caithness ; they split up into the same long lines 

 of sea-cliff, they are swept by the same stormy seas, and 



