SKY. GEOLOGY. SECONDARY STRATA. 349 



the oblique. It hence also follows, that if the fissile 

 property of clay slate is the result of some internal 

 arrangement analogous to crystallization, we are equally 

 entitled to attribute the structure of this sandstone to 

 the same cause. The inclination of the oblique lamina 

 to the horizontal, varies from 10 to 30 ; but it is 

 regularly in the same direction, the dip, if it may be so 

 called, being to the south. This appearance is neither 

 rare nor dubious, but is extremely well marked, and 

 predominates throughout the whole range. The measure- 

 ment of the parts having been mislaid, it is from recol- 

 tion that the intervals between the horizontal lines are 

 here stated to vary from one foot to a foot and a half. 

 There is no difference in the quality of the two sets of 

 laminse, both being of white sandstone, generally more 

 or less calcareous.* 



To enter more minutely into the composition of these 

 beds, I may now remark that the sandstone often acquires 

 the aspect of some of the most compact and crystalline 

 varieties of quartz rock, while in other cases it has the 

 lax texture of an ordinary freestone. In some places it 

 is calcareous; the calcareous matter varying so much in 

 quantity that the compound would sometimes be called 

 a calcareous sandstone, while at others it would be 

 described as a siliceous limestone : in the latter cases 

 it is often dark brown, grey, or even of a dark lead 

 blue. The beds of mere limestone are rare, and those 

 which I observed lie towards its upper boundary : they 



* Having mentioned the resemblance which the channelled surface 

 of this sandstone bears to certain architectural ornaments, I may point 

 out to artists the probable origin of some varieties of the hatching and 

 vermiculation of rustic work, in the various modes of weathering dis- 

 played by many of the sandstones. In many instances the imitation of 

 art is perfect; and among other places I may name an example at Iloslin 

 Castle, where the resemblance is so strong that it is at first sight difficult 

 to believe that the chisel has not been employed in giving the stones 

 their present appearance. 



