244 GEOIiOGY OF THE ISLE OP WIGHT. 



compressed that the breadth of their outcrop is less than their 

 true thickness. 



Between Ashey and Newport the strata below the Bembridge 

 Limestone still continue nearly always vertical, though not quite 

 so much compressed. In several places there seems to be a 

 tendency to develop small secondary plications parallel to the 

 main fold but not traceable more than a few hundred yards. 



West of the Medina the Bembridge Beds, though dipping at 

 high angles, are seldom or never vertical, but the borings at 

 Gunville show that the Hamstead Beds are still much tilted. 



These variations in the extent to vs^hich the Tertiary formations 

 have been influenced by the monoclinal curve seem at first to point 

 to variations in the height or sharpness of the curve. But they 

 may be otherwise simply explained. If a series of curved strata 

 were cut through at different levels the age of the beds most 

 strongly tilted would be found to vary considerably. If the 

 country at Ashey were lowered one or two hundred feet by 

 denudation the Bembridge Limestone at the surface would only 

 dip at low angles, and more of the Secondary beds would appear 

 to be affected by the disturbance. Any such lowering of the 

 surface leads to an apparent shifting of the verticality into a lower 

 geological horizon and an apparent shifting of the line of greatest 

 disturbance towards the south. Thus the apparent dying out of 

 the syncline eastward may really be the result of an upward tilt 

 in that direction, causing the curve to be cut through at a lower 

 level, but not affecting the thickness of the beds affected or the 

 real height of the curve. (Fig. 84.) 



Fig. 84. 



Diagram Section to shoto variation in the dip of the Strata as 

 the Surface is lotoered. 



Where the strike of the rocks turns sharply southward at 

 Calbourne, the angle of dip rapidly lessens and the width of 

 the several outcrops correspondingly increases. At Shalcombe, 

 however, where the former strike has been resumed, the lower 

 beds are again vertical, while the Osborne and Bembridge Beds 

 occupy long dip slopes. The sudden curve of the strata to the 

 south and re-appearance of the high angles along a new line 

 is connected with the dying out of an anticline, which cannot 

 be traced west of Calbourne, except perhaps in the lower angles 

 of the dips in the southern part of the long slope of Bembridge 

 Limestone. A slight indication of the flattening of the beds may 

 also be found in Freshwater, and even as far as Totland Bay. 



