,64-0 Contrihutkms to the 



to penetrate, consists of these strata; the marly sandstone 

 being most predominant, and the limestone only occurring in 

 thin beds. The northern half of the river is floored with the 

 same sandstone ; from which it is evident that the bank, to this 

 extent, has been worn away and destroyed by the force of the 

 stream and other auxiliary means. The gradual waste of the 

 sandstone seems to be accelerated by two agents. The rock 

 is naturally very hard ; but, by the constant action of water 

 upon it (for we find it generally moistened by numerous 

 springs which trickle down over its whole surface), it shivers 

 into slaty fragments ; and these again are converted into a 

 coarse powder, which is borne away by the stream. 



The water which drops from these rocks has the property 

 of what is commonly termed petrifying, which is produced by 

 a solution of bicarbonate of lime, and shows that it has been 

 subjected to pressure. 



But a still more powerful agent is the frost of winter. The 

 rock, when gently heated in the fire, is found to lose much of 

 its weight : this loss of weight is accompanied with decrepita- 

 tion ; which shows that the moisture is not chemically com- 

 bined, but mechanically deposited between its plates. During 

 winter, the water freezes, expands, and splits the rocks, which 

 crumble and decay. 



About a foot above the level of the river there are two beds 

 of red massy gypsum containing crystals, and a thin bed of 

 white fibrous gypsum. The former is hydrous sulphate of 

 lime, containing one half per cent peroxide of iron. 



The highest part of the bank, which is called Hindlaw 

 Top, exhibits, perhaps, the most characteristic section of the 

 strata, although the sulphate of lime beds are thicker higher 

 up. Hindlaw Top is about 50 ft. in perpendicular height, by 

 measurement. 



This marly sandstone occurs in connection with a white 

 variety, which contains less carbonate of lime, and is more 

 compact in its structure : it occurs at Lochton, and on the 

 east of Birgham Haugh, having a slight dip to the south-west. 

 The same rocks can be distinctly traced along the Tweed to 

 Coldstream, and up the banks of the Leet to Swinton ; and, 

 near Belchester, contain thin beds of gypsum. 



The sandstone at Eccles belongs to the same formation ; 

 and here it becomes an excellent building-stone, highly excel- 

 ling in durability, and seems to have been quarried for at least 

 700 years. The ancient convent of Eccles was founded a 

 second time in 1154«, according to Hoveden and the Melrose 

 Chronicle ; and it appears to have been built of this stone. 

 The ruins of this nunnery still exist ; and, if we may judge 



