THE STRUCTURE OF THE ISLAND 13 



there that the forces wearing down the land are most 

 effective. 



We must notice another thing which happens when 

 rocks are being upheaved and bent into curves. The 

 strain is very great, and sometimes the strata crack and 

 one side is pushed up more than the other. These cracks 

 are called faults. At Little Stairs, about half way 

 between Sandown and Shanklin, two or three faults may 

 be seen in the cliff. The effect of two of the faults may 

 be easily seen by noticing the displacement of a band 

 of rock stained orange by water containing iron. The 

 strata are thrown down towards the north about 8 ft. 

 A third fault, the effect of which is not so evident at first 

 sight, throws the strata down roughly 50 ft. to the south. 

 These are only small faults, but sometimes faults occur, 

 in which the strata have been moved on opposite sides of 

 the fault thousands of feet away from one another. We 

 might think we should see a wall of rock rising up on the 

 surface of the ground where a fault occurs ; but the faults 

 have mostly taken place ages ago ; and, when they do 

 happen, the rocks are generally moved only a little way 

 at a time. Then after a while another push comes on the 

 rocks, and they shift again at the same place, and go a bit 

 further All this time frost and rain and rivers are working 

 at the surface, and planing it down ; so that the uneven- 

 ness of the surface caused by faults is smoothed away ; 

 and so even a great fault does not show at the surface. 



As we follow the Sandown anticline westward it gradu- 

 ally dies away, the upheaved area being actually a long 

 oval what we may call a turtle-back. As the Sandown 

 anticline dies out, it is succeeded by another a little 

 further south, the Brook anticline. There are in fact a 

 series of these east and west anticlines in the Island and 

 on the adjacent mainland, caused by the same earth 

 movement. As a consequence of the arching of the strata 

 we find the lowest beds we saw in Sandown Bay running 



