Dr. Mac Culloch 071 Quartz Rock. 451 



in breadth from one mile to six, is fundamentally composed of this 

 one rock, which is also to be found extending through Scarba on 

 its northern, and through a great portion of Isla on its southern 

 shore. The other rocks which occur, with the exception of an 

 important series to be immediately described, either occupy small 

 spaces apparently subordinate to the general mass, or consist of veins 

 which traverse it. The highest part of this tract forms an irregular 

 elevation, of which the three well-known Paps of Jura attaining 

 the height of 2500 or 2600 feet, are the most remarkable and 

 prominent features. These occupy a point in the island much 

 nearer to the southern than to the northern extremity. The in- 

 terval between them and the southern shore is low, the mountains 

 declining with a tolerably uninterrupted slope to the sea. But 

 that between the Paps and the northern side is occupied by a suc- 

 cession of hills which also decline gradually from the highest 

 elevation, and form a broken ridge extending to the northern shore 

 of the island. If we look from any of the highest summits to- 

 wards the north, a view of almost unexampled singularity and 

 grandeur is afforded. A series of ridges and broken elevations ap- 

 pears under the eye, but so far beneath it that their irregularities 

 are nearly lost in the continuity of the straight lines which guide 

 the sight to the further extremity of their range. These seem to 

 rise from beneath the feet, and to converge to a distant centre, ac- 

 cording to the strict laws of perspective. On investigating the 

 cause of this striking disposition, it is easy to perceive that the 

 effect is produced by the disrupted edges of strata of rock rising 

 from the east at a considerable angle, and broken away towards 

 the west. 



However much the continuity be here and there apparently in- 

 terrupted by the predominance of some particular hill, it is obvious 



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