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The Pamphlet Collection of Sir Robert Stout: Volume 22

V. Moraines

V. Moraines.

One conspicuous feature connected with the Glacial phenomena of Orkney is the remarkable absence of any traces of local glaciers except in Hoy and the Mainland. When we consider the abundance of moraine heaps in all the more important islands of the Shetland group, this difference seems all the more striking; but when we remember the marked contrast between the physical features of the two groups of islands, the difficulty at once disappears. As we have already indicated, the only mass of elevated ground which would be capable of nourishing a series of local glaciers, after the great mer de glace had melted back from the Orcadian coast-line, occurs in Hoy. Hence we find that in the valleys which drain the group of conical hills in the north of that island moraines occur in abundance and also of great size. Professor Geikie has already described several examples which also came under our notice*. In the valley to the page 659 east of Hoy hill a moraine mound, nearly half a mile long and from fifty to sixty feet high, runs across the mouth of the glen. It would seem that the later glacier which filled the valley did not succeed in scooping out the moraine profonde belonging to the primary glaciation, as the moraine matter rests on stiff sandy Boulder-clay. Further, in the hollow below Coulax hill several concentric heaps were observed which extend across the valley, indicating pauses in the retreat of the glacier.

In the Mainland also the moory ground between Finstown and Maes Howe is dotted all over with conical moraine heaps, evidently deposited by the glaciers which moved off the northern slopes of the Orphir hills. On the east side of the range of hills that runs north from Finstown several parallel moraine ridges may bo observed not far from Ellibister. Again, in the peninsular tract to the south-east of Kirkwall, a splendid series occurs in a valley situated about three miles north of Graemshall. At the point where the highroad from Roseness joins that from St. Mary's to Kirkwall, the concentric arrangement of the moraine heaps is admirably displayed.

* 'Nature,' vol. xvi. p. 415.