Anniversary Address. 5 



" All the peaks are porphyry; on the summit of the middle 

 peak, it is of a dark dull red colour, having a few felspar 

 crystals scattered through a felspathic base ; lower down, it 

 is a light red compact felspar. In the northern peak, the 

 porphyry is of the common character, a red or greenish 

 felspathic base with felspar crystals ; but, according to Mr 

 D. Milne Home, clinkstone, containing embedded greywacke, 

 occurs in the southern peak ; and opposite Bowden it is in 

 pentangular columns. These however we had not time to 

 visit. 



" Near to Melrose, in St. Mary's glen, which has been hol- 

 lowed out by a little burn, there is a peculiar sandstone, of 

 which we saw about 30 feet in thickness. It is soft and 

 friable ; the beds are flat, dipping very slightly W.S.W. ; but 

 no fossils could be detected, and therefore its relative age 

 cannot be determined with certainty. It has, however, the 

 aspect of the old red sandstone, being of a deep red colour, 

 and resembling much some sandstone beds on the Whiteadder 

 above Preston bridge, which are of undoubted Devonian age. 

 A trap tufa dike cuts through this sandstone in St. Mary's 

 glen, indurating the beds on the west side, while those on the 

 east appear unaltered. 



" A short distance southward of Melrose, a remarkable rock 

 is quarried for a building stone. Seen in the mass it has the 

 appearance of a fire formed rock, being devoid of stratifica-. 

 tion, and irregularly divided by joints. It is composed of 

 fragments of porphyry and greywacke, some being angular 

 and others rounded, firmly united in a felspathic base. Pro- 

 perly speaking it is a Breccia ; and it is evidently of later 

 age than the porphyry, and later too than the red sandstone, 

 for the dike which cuts through this sandstone in St. Mary's 

 glen is of a similar character. Probably it may have origin- 

 ated in an eruption of mud, which enveloped fragments of 

 porphyry and greywacke, and which, though suificiently 

 heated to alter the sandstone, was not so intensely heated, as 

 to fuse the fragments and form them into a new crystalline 

 rock. The porphyry of the Eildon is similar to that of the 



