INYERTED POSITION. 139 



HORIZONTAL POSITION. Stratified rocks were originally 

 dej osited in a horizontal, or a nearly horizontal position, as 

 here depicted (fig. 59), agreeably to the law by which fluid 

 substances find their level ; the fact is demonstrated by the 

 circumstance, that fossils are always deposited conformably 

 to the planes of stratification. This circumstance is beauti- 

 fully exhibited in the cliffs of Alum and Whitecliff Bays, 

 in the Isle of Wight, where rows of flints and silicified 

 sponges, originally deposited in a horizontal position, are 

 now lifted quite upright, with the beds of chalk which 

 contain them. 



Fio. 59. 



DISTURBANCE OF THE STRATA. Subsequently to their 

 deposition, the strata have, in many instances, undergone 

 disturbance, and have been raised at various angles with the 

 horizon. 



VERTICAL STRATA. Occasionally they are lifted almost 

 to a vertical position, as in the following illustration, exhib- 

 iting the Silurian strata on which Powis Castle is built.* 

 The chalk and tertiary beds at Alum' and Whitecliff Bay, in 

 the Isle of Wight, are likewise nearly vertical. 



FIG. 60. 



INVERTED POSITION. In some cases, by the intrusion of 

 igneous rocks, they are actually inverted, and turned back, 

 as instanced in the Malvern hills (fig. 61). 



* Sir R. Murchison's Silurian System. 



