458 MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



The dyke has been quarried from A to E, patches only being left here and 

 there, and especially at the angles, where the rock proved not to be good for road- 

 metal. It will be observed, that it runs most frequently parallel with and between 

 the strata of greywacke, and that it occasionally cuts across them. Its width in 

 the Rink Quarry varies from 16 to 30 feet. 



Between the Rink Quarry and the Jed, there are several quarries on the line 

 of the dyke, and which, from the Rink Quarry, bear N.W. 2 N. The rock is not 

 perceptible in the channel of the river ; but its course up the face of the brae, on 

 the opposite side, is very perceptible. The progress of the dyke to the northward 

 I shall point out, from a very distinct account of it furnished to me in writing by 

 Mr OLIVER of Langraw, who. at my request, travelled along that portion of its 

 line to be now described. Mr OLIVER states,* that " at Roughlee Nook, the dyke 

 appears to be about 20 feet wide ; but where, as in this instance, there has been 

 no section by water or digging, it is very difficult to ascertain the width. There 

 appeared here to be, on each side, 4 or 5 feet of a dark-coloured mass, compact 

 and heavy, but not crystallized like the material of the dyke proper. This is on 

 the border of the porphyritic formation. At Falside, the dyke, 30 feet wide, runs 

 through red sandstone, which is also changed, where in contact, into a material 

 similar to that described above, gradually assuming its natural character as it 

 recedes. The adjoining strata do not seem at all deranged. From Falside, the 

 next point, near Abbotrule, bears nearly north-west by north. Here the dyke is 

 intersected by a burn, and its side exposed for 30 or 40 yards along a bank. The 

 material on each side of the dyke is a red and white (mottled and streaked) sand- 

 stone, which at some points is changed into a hard dark-coloured stone, some- 

 what resembling ironstone, but which gradually regains its natural features as it 

 recedes from the dyke. In other places, quartzy pebbles, without any other very- 

 considerable change in structure, indicate the action of heat. There is no dis- 

 cernible change in the direction of the adjacent strata, which, however, are highly 

 inclined, dipping to west by north, at an angle of about 20. Width of dyke about 

 20 feet ; direction, as far as seen, west north-west ; but between this point and 

 Hallrule Mill, the direct line runs nearly west by north. At Hallrule Mill, the 

 dyke cuts through the sandstone, without, so far as can be seen, effecting any great 

 changes. From this, to the next point of view at Glen planting on Caver's estate, 

 the course is due west. Here the dyke is seen for 200 or 300 yards running west 

 north-west, and is 18 feet wide, when suddenly it changes to 30 feet for a short 

 distance, and then suddenly reverts to its previous dimensions (18 feet), and at 

 the same time changes its direction to west south-west. The dyke at Glen Quar- 

 ry has been quarried out to a considerable extent, and to a depth of about 30 feet 

 the sides, nearly perpendicular on either hand of the dyke, being left standing. 



* It is proper to premise, that the bearings given by MR OLIVER are true, and not magnetic. 



