16 Mr. Winch on the Geology of the Banks of the Tweed. 



Opposite Newbiggin, the elevated cliffs are rendered sin- 

 gular by an escarpment of bright red marl, which, from a 

 distance, is a striking object. The dip is towards the south- 

 east. Near Norham Boat-House, the Tweed sweeps round 

 the foot of a promontory of not less than seventy to eighty feet 

 in height ; its rocks are red, and differ in no respect from those 

 a little higher up on the north bank of the river. To the 

 eastward, Norham Castle stands upon an eminence overlook- 

 ing the Tweed, and, as the stones of which it is constructed 

 are red and white, the vicinity of quarries of both these kind 

 of rock is evident; but the geology of its immediate neigh- 

 bourhood may be studied to most advantage by carefully in- 

 specting the abrupt cliffs below the Castle mount. A beautiful 

 and interesting section is there developed. The lowest bed, 

 which is scarcely above the level of the stream, consists of a 

 whitish sandstone and limestone forming a breccia; on this 

 rests a stratum of reddish sandstone, forty feet thick, which 

 is, in turn, capped by fourteen thin seams of soft ash-coloured 

 limestone, interstratified with an equal number of others of 

 greenish -gray slaty marl, mixed with sand and silvery mica; 

 their aggregate thickness is twenty-five feet, which, with five 

 feet of diluvium, will give seventy feet as the elevation of the 

 escarpment. When viewed from below, the upper part of this 

 singular cliff appears to be striped with the regularity of a 

 ribbon. In the thick bed of sandstone, pear-shaped nodules 

 of extremely hard white micaceous sandstone abound, and 

 greatly impede the Work of the quarry-men ; some of these 

 nodules are not many inches in diameter, but I measured one 

 of two feet and a half; they are not ranged in lines, but their 

 sharper extremities point towards the north-west, which is the 

 full rise of the stratum containing them. Proceeding eastward 

 to the vicinity of Horncliffe House, the rocks are still red 

 sandstone, with similar calcareous seams as those near Nor- 

 ham resting upon them, and a cut, made to widen the road to 

 the Chain Bridge, lays open thirty feet of rock, comprising 

 six different strata; the lowest is red sandstone, the others 

 limestone and slaty indurated marl. A slip of six feet cuts 

 through these beds. Above West Ord, a cliff' of sixty feet 

 again exhibits the nature of the rocks ; here the variegated 

 sandstone rests upon the red, which is filled with nodules of 

 red ochre, and is covered by the calcareous series so fre- 

 quently mentioned ; and at the plantations, a little lower down 

 the river, six alternations of these thin beds are covered by 

 thick strata of red and variegated sandstone. At Ord Mill, 

 the red rock alone is visible ; the dip of the whole series is 

 southward of east. Diluvium now covers the rocks on the south 



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