UPPER SHALE. 59 



position, at least in respect of the greater part of their respective 

 masses, at the place of junction. Their present relative positions can- 

 not be accounted for, but on the supposition of a dislocation of the 

 strata, similar to what we shall have to notice hereaftei', in not a few 

 instances. The chalk must have slipped down in an immense mass 

 upon the shale, and displacing it by the pressure, forced it up into 

 its present elevated position. The appearance of the chalk at this 

 point, and its known tendency to split vertically, confirm this idea. 

 On a careful inspection of the chalk cliff over the shale, we can per- 

 ceive that large portions of the upper chalk have descended from a 

 higher station to that which they now occupy; though the uniformity 

 of their colour, and their retaining the same vertical position in their 

 columnar masses, serve to conceal the dislocation. Even the coloured 

 chalk has not been exempted from this kind of violent abruption; 

 for at a little distance from the junction with the shale, we find a 

 break in the clift", rendered very conspicuous by its crossing a seam 

 of red chalk, which is higher on one side of the fissure, and lower on 

 the other. 



The softness of the slate-clay would make it more easily forced 

 out of its natural position by the descent of the chalk : for though in^ 

 the greater part of the bed it is not plastic, but has its proper schist- 

 ose form, still it is much softer than the aluminous schistus in the 

 great bed on the Whitby shores; and it is not interstratified with 

 any of those seams of sandstone or limestone, Avhich, usually in- 

 tersect and strengthen the beds of schistus. It contains, however, 

 like our other beds of shale, a great number of septaria and other 

 nodules, with numerous petrifactions ; and as some of the petrifac- 

 tions, particularly among those found at Settrington, appear imbedded 

 in fragments of a kind of schistose argillaceous limestone, it is not. 

 unlikely that a seam of that description may exist in the lower part 

 of the schistus. Some of the nodules containing petrifactions, found 



