ON THE NATURAL HISTORY OF THE SOUTH OF SCOTLAND. 233 



undulated and contorted. The general dip is to the west, and the direction N. W. 

 and S. E. 



The diluvium consists of clay, gravel, and pebbles, the latter being of grey- 

 wacke, slate, quartz, and Lydian stone, but without any intermixture of frag- 

 ments of primitive or secondary rocks, so far as I have observed. The soil is 

 clayey and gravelly or pebbly. The vegetation is in no respect remarkable, nor 

 is the scenery at all picturesque. 



From Whitebanklee or Thornylee the scenery is greatly improved, the river 

 winding through a deep wooded valley to the bridge near Reclees, where the bed 

 is rocky, and causes rapids of considerable beauty ; but even here, and until we 

 reach the mouth of the Ettrick, no remarkable geological appearances present 

 themselves. 



The Valley of Selkirk is several miles in length, and upwards of half-a-mile in 

 breadth, the greater part of its bottom occupied by the river, and the broad peb- 

 bly beaches which it has formed, and which resemble those of the Spey at Fo- 

 chabers. The inclosing hills are low, with long slopes, their sides cultivated, or 

 covered with wood. The town of Selkirk, which stands on the brow of a hill, on 

 the eastern side of the valley, is built on a pale-coloured, small-grained grey- 

 wacke, intersected with veins of pink or white calcareous spar. The diluvium is 

 very deep along the declivities, and consists of clay and sand, mixed with peb- 

 bles of transition rocks, without any fragments of the primitive or secondary 

 series. 



The range of low hills separating the Tweed from the Yarrow, is of the same 

 general nature, the strata being of small-grained grey-wacke, which, in decom- 

 posing on the exposed parts of the summits, often becomes white, and sometimes 

 reddish, in which latter case one might at first take it for red sandstone. 



The upper part of the open valley in front of Bowhill and the]mouth of the 

 Yarrow, although possessed of considerable beauty, offers no remarkable pheno- 

 mena, excepting a very high bank of diluvium. We may, therefore, ascend the 

 celebrated pastoral stream which flows from St. Mary's Loch. Along the lower 

 part of its course as far as Newark Castle, the strata of small-grained greyish- 

 blue grey-wacke, alternating with thinner beds of soft shale, are nearly horizontal 

 in many places. Beyond Newark the valley of the Yarrow, which is narrow, 

 winds among the green hills, and towards the lake opens up a little, 

 especially on the northern side. The stream is of inconsiderable magnitude, 

 with darkish water, and a rapid current. It flows over a pebbly bed in its 

 whole length, leaving beaches of considerable breadth, and in some places 

 has cut the diluvium so as to leave gravelly banks from ten to twenty feet in 

 height. It seems to have little influence on the vegetation along its banks, 

 scarcely any natural wood occurring in its course. In the lower part of the val- 

 ley, however, the defect is compensated by pretty extensive plantations. 



