KAISED BEACHES, CLIFF AND RUBBLE HEADS. 221 



Mr. Carey gives the elevation of the ledge deposit in the 

 cave as 24 feet above mean sea-level, consequently the erosion 

 of the sides of the passage must either have been produced by 

 a sea much higher than our present one or by storm waves 

 acting on the deposit from the present level, with the three 

 or four feet of passage below the eroded part closed to their 

 action. But if the latter, the erosion is carried back into 

 past time, a much longer period than most of us would be 

 willing to admit, for the lower sides of the passage show the 

 wear of long periods. Again, if the present sea-level, even 

 assisted by storm waves, had produced the erosion, surely the 

 lines of erosion marked in the solid rock would be obliquely 

 downwards and outwards, but instead of that they are de- 

 cidedly horizontal and at an elevation of from three to five 

 feet over the present floor of the passage. I cannot pretend 

 to formulate a theory that agrees with all the observed facts, 

 but I think the idea of the cave having been filled from the 

 present passage is disproved by the high level of the conglo- 

 merate on the roof, which is some 15 feet above the ledge, in 

 some spots quite 40 feet above the present mean sea-level. 



Mr. Carey has taken the trouble to run a series of levels 

 to the top of the spring high tide of the 5th of October, 1891, 

 and found that mark to be 17 feet above the mean sea-level 

 adopted. We have this series of facts to account for : — 



1. — A deposit of pebbles in a cave extending between 



22 and 40 feet above mean sea-level. 



2. — A well marked and firmly conglomerated portion 



showing apparently the position of the main deposit, 



24 feet above mean sea-level. 



3. — Present high water mark (spring tides), 17 feet 



above mean sea-level. 



4. — A corroded channel, horizontally grooved, 7 feet 



above high water spring tides. 

 At the same elevation as the main deposit in the cave is 

 found a number of patches of semi-hardened raised beach 

 along the shores of Moulin Huet. These extend from the foot 

 of the roughly-paved slip to the cave described. This line of 

 beach is irregular and interrupted, but it is evidence of a past 

 beach of somewhat the same type as the present one, but no 

 doubt considerably above it. We may assume that most of 

 these patches are of the same period as the cave deposit. 



Such patches are found in two places between Moulin 

 Huet and Petit Port, viz., at the Silver Mine,* and at the base 

 of the serpentine path leading to the smaller bay. These 



* See Mr. Derrick's paper previously quoted, ... 



