304 LADY McEOBEKT OX ACID AXD OTHEll [Dec. 1914,. 



II. Relation to the Uppee Old Eed Sandstone. 



The more easterly masses, such as White Hill, Black Hill, and 

 Bemersicle, are associated with the main outcrop of the Upper 

 Old Eed Sandstone of Roxburghshire. The more westerly, though 

 situated in advance of this outcrop, in a region predominantly 

 composed of Silurian greywackes, have in certain cases sheltered 

 small outlying patches of Old Red Sandstone. Dr. Peach, 1 who 

 mapped the district for the . Geological Survey, shows a some- 

 what extensive outlier of Upper Old Red Sandstone forming 

 the pedestal of the Eildon Hills, and a long strip at the side 

 of the Chiefswood neck. Mr. J. Pringle 2 has described a minute 

 patch at Wbitelaw Hill, Fox's Cover, and Oakwood Mill; in 

 each of these cases it is associated with the igneous intrusions, 

 and I have recently found another under the Bowden-Moor Quarry 

 trachyte. There is also a patch of Old Red Sandstone on the 

 south-eastern flank of Cauldshiels Hill. Although it is not 

 particularly weU exposed, I have been led to believe that a good 

 deal of it was got out of the quarry when first worked. 



The evidence for these various outliers, except that alongside 

 of the Chiefswood neck and the Eildon Hills, is far from easy 

 to find. The presence of the Bowden-Moor Quarry outlier is 

 betrayed by numerous bits of hard quartz-grit, stained deep red, 

 lying beneath the turf on the south-eastern flank of the hill, just 

 above the farmhouse. At Wbitelaw Hill a coarse yellow grit 

 is found at the south-east side of the cap of trachyte, and is 

 attributed by Mr. Pringle to the Upper Old Red Sandstone. At 

 Cauldshiels Hill, baked yellow and red sandstone and mudstone 

 occur on the south-east side of the trachyte-dyke, below the 

 old fort. 



The main purpose of the present paper is petrographical. On 

 account of their striking position dominating Melrose, and their 

 curiously barren aspect, the Eildon Hills have so far attracted more 

 attention than the other intrusions. As early as the ' forties ' of 

 last century, Prof. Forbes gathered a small collection of typical 

 varieties from the Eildons. This material is still preserved in the 

 Hun terian Museum, Glasgow ; but no description seems to have 

 been published. Dr. Peach, in the Greological Survey map of 

 the district published in 1879, gives a useful classification of the 

 igneous rocks of the Melrose district under three headings : 

 intrusive basalt, intrusive felstone. and volcanic agglomerate — the 

 last-named in necks of Calciferous Sandstone age. An important 

 petrographical advance was accomplished by Mr. T. Barron s in 

 189(3. He examined rocks from the Eildon Hills and the Black 

 Hill, and demonstrated the occurrence of the rare amphibole 

 riebeckite in the Mid Hill of the former group. He believed 



1 In Sheet 25, Geol. Surv. 1-inch map, published in 1879. 



2 ' Notes on Three Small Outliers of Old Red Sandstone in the Neighbour- 

 hood of Selkirk ' Trans. Edin. Geol. Soc. vol. ix (1909) p. 351. 



: * Geol. Mag-, dec. 4, vol. iii (1896) pp. 373-75. 



