1882-83] Edinburgh Naturalists Field Club. 1 17 



WEST LINTON TO DOLPHINTON— /«»c 10, 1882. 



Our walk to-day lay over the old red sandstone, which in the 

 Pentland district is faulted down between the Silurian greywacke 

 on the S. and S.E. and the carboniferous on the W. Towards 

 the south stretched the Peeblesshire hills, rising peak over peak, 

 " with long smooth summits that join on to each other, and once 

 formed a wide tableland." About a mile west rises Mendick Hill 

 (1500 feet), formed of brownish conglomerate, and capped by 

 jjorphyry, which has protected it from denudation. 



Above the bridge at Linton are a series of beds of sandstone, 

 which gradually pass into a calcareous claystone. They are almost 

 horizontal, but change suddenly about 200 yards above the bridge. 

 The beds vary much in colour and hardness — being harder in pro- 

 portion to the quantity of lime. 



PEEBLES— JifHc 1, 1882. 



Peebles is situated in one of the valleys of the great Lower 

 Silurian tableland of the south of Scotland. The rocks of the 

 neighbourhood, as seen in the quarries and along the basin of the 

 Tweed, consist of hard grey and blue grit, shale, and greywacke. 

 The last is exceedingly hard, locally termed whinstone, and much 

 used for road-mending. The surface-soil and underlying strata in 

 the valleys generally date from the Ice Age. At the railway 

 bridge above Neidpath Castle there is a fine section of boulder-clay 

 and its accompanying beds. The fertile meadow-lands on either 

 side of the Tweed are good examples of the flood-plains of alluvium 

 which our rivers form as a slight return for the tremendous waste 

 of their channels. 



FALKLAND AND LOMOND HILL-/«7ic 24, 1882. 



This district lies on the northern boundary of the carboniferous 

 sandstone series, where this passes into the old red sandstone of 

 the Ochils and Dura Den, The hills are of sandstone capped by 

 greenstone, which has protected them from denudation. West 

 Lomond is particularly interesting as an example of the power of 

 a river to cut its way downward through solid rock. The sand- 

 stones rise for 900 feet above the vale of Eden, the bare edges of 

 the strata sometimes jutting through the green hill slope. These 

 are capped by a thick bed of greenstone, which is in turn covered 

 with beds of sandstone and limestone, and finally the greenstone 

 of the summit. The truncated edges of the sandstone are faced by 

 similar strata on the other side of the valley. It is evident the 

 river has cut its way down through them at least 900 feet. 



