438 MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



Ruberslaw (where the stratum is 12 feet thick), and rising towards the hill at an 

 angle of 15. At both of these places, there are the usual red strata, lying over as 

 well as under the white beds. I understand that beds of similar white sandstone 

 have been quarried at Pinnacle on the Ale- water, in South-dean parish, and also 

 in Jedburgh parish, at Tudhope and Ferniehirst.* 



The yellow variety of sandstone, existing at least among the old red rocks, 

 occurs at only two places known to me, viz. at St Boswell's Green and Kirklands. 

 At the former place it is quarried. I understand it occurs also at Bedrule. 



These red rocks, which prevail so extensively through Roxburghshire, are 

 almost everywhere horizontal. They preserve their horizon tality even at the sides 

 of trap hills, some of which (as, for example, the Dunion, Ruberslaw, Peniel Heugh) 

 being entirely surrounded by them, look like black rocky islets in a red sea. 



There are few places where the strata in this formation exhibit any consider- 

 able dip. On Jed-water below Edgerston, the strata dip towards the north at an 

 angle of 25 ; on the south side of Lilliard's Edge, they dip to the south-west at 

 an angle of 30 ; at Plewlands quarry, in the parish of St Boswell's, they dip south 

 at an angle of about 20 ; to the north of Hunthill, they are nearly vertical owing 

 to a local dislocation. 



There are sometimes on these red sandstone rocks curious spots and blotches 

 of a white and bluish- white colour. The spots are generally spherical, the spheres 

 being an inch or two in diameter, or less. Sometimes the blotches are of no determi- 

 nate form, and occupy a number of square feet in their sectional area. The origin 

 of these white spots and patches is not very obvious. It is not in the least probable, 

 that the red sandstones could have been deposited with spheres of white sand in 

 the heart of them. The colour has more probably been discharged by chemical 

 action, subsequently generated at these places ; a conclusion confirmed by the oc- 

 currence, in the very centre of many of these spheres, of a small pea of metallic 

 oxide, to which the iron originally diffused through the stone seems to have been 

 transferred. 



The spherical white spots now referred to, must be familiar to every one ac- 

 quainted with the old red sandstone formation in other parts of Scotland. I be- 

 lieve that they are not confined to this class of rocks, and in particular, that 

 they occur likewise in the new red sandstone. But though the phenomenon is 

 common, I do not think the cause of it has ever been distinctly explained. I 

 shall therefore venture, in the second part of this memoir, to throw out some sug- 

 gestions on that point. 



* Tudhope quarry is three-fourths of a mile north of Jedburgh, whilst Ferniehirst quarry is on the 

 south side of the same valley. The rocks are, at both places, nearly horizontal ; and being on the same 

 level, as well as of the same colour, which is not a common one in the district, it is not improbable that 

 they are portions of the same stratum, which originally stretched across the valley, before it was scooped 

 out. 



