TRANSACTIONS OF THE SECTIONS. 625 



greater number of the isolated hills, that are outliers from the 

 mountain chain of the Lammermuirs. 



Mr, Milne then described the external appearance or confi- 

 guration of the district as that of an oval-shaped basin, cut 

 across at the east end by the German Ocean, and the northern 

 edges of which are the grauwackd hills, some of which rise 

 1800 feet above the level of the sea. The country then slopes 

 down to the valley of the Tweed, and is diversified by a number 

 of tributary streams, which easily cut and form deep ravines in 

 the soft clay strata, of which the lower parts of the country are 

 chiefly composed. Next to the grauwacke formation, in point 

 of level, is the old red sandstone group, which ranges along the 

 base of the Lammermuir, Galawater, and Cheviothills, and occu- 

 pies perhaps one fifth of the intervening space, between the hills 

 and the Tweed, but is never visible at a lower level than 200 or 

 300 feet above the sea, or higher than 900 or 1000 feet above 

 the sea. The coal-measures and marl strata occupy the west 

 and lowest parts of the surface of the basin, being cut through 

 by the Tweed, in its course from Kelso to the sea ; the higher 

 parts of the river, above Kelso to Jedburgh, displaying sections 

 of the old red sandstone. 



After this general sketch of the three several deposits of stra- 

 tified rocks in this district, Mr. Milne proceeded to notice the 

 situation of the trap-rocks, the exact boundaries of which, he 

 said, it was more difficult to describe ; though it may be re- 

 marked that they occur most abundantly in the grauwacke and 

 the old red sandstone series. The traps in these two different 

 groups also possess very distinct characters, the grauwacke trap 

 being remarkable for its compactness, and the old red sandstone 

 trap being of a looser and more friable texture. Almost all the 

 isolated hills, which diversify the appearance of the upper parts 

 of Berwickshire, as Cowdenknowes, the Dirringtons, Cockburn 

 Law, Lamberton, Home Castle, Kyles's Hill, and others of in- 

 ferior note, consist of this less compact trap, and all occur 

 within the limits of the old red sandstone. 



Mr. Milne then entered into a more detailed account of these 

 different formations, pointing out some circumstances charac- 

 terizing each of them. 



I. The Grauwacke Hills. — These have been usually de- 

 scribed as running from St. Abb's Head across the country to 

 the Irish Channel. Though this is true as a general remark, 

 yet, on an examination of these hills in detail, it is found that 

 a considerable portion of them, perhaps |th or ^th, consists of 

 trap-rocks intermixed. One half of the promontory of St. 

 Abb's Head consists of trap; and there are few sections in the 



1834. 2 s 



