﻿Vol. 66.] 



JURASSIC STRATA OJF SOUTH DORSET. 



59 



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gave no result, and then was found a block with many specimens of 

 fine-ribbed Dumortierice, indicative of moorei hemera. 



The important point about this 

 part of the section is that there 

 are more than 40 feet of strata 

 deposited during the hemene 

 aalensis and moorei. In the Cot- 

 teswolds the amount of deposit 

 during these dates was only a few 

 inches — -so insignificant that sepa- 

 ration of the distinctive deposits 

 is not easy. Here there is no 

 doubt about the sequence ; and, 

 further, change even in the cha- 

 racter of the Ammonites of the 

 aalensis pattern (Canavarina) can 

 be noted : the finer-ribbed forms 

 are later than the coarser-ribbed, 

 as is right in a catagenetic series. 



Below the moorei bed is a series 

 of yellow sands and sandstones, 

 made out roughly by the level to 

 be about 100 feet thick, down 

 to the spring of water in the road 

 near the top of the hill east of 

 Chideock. This water is held up 

 by the clay-bed which forms the 

 top of Down Cliffs. 



The beds have noAv to be studied 

 on the sea-coast. Here, between 

 Seatown and Eype, are four pro- 

 minences of the cliffs with hollows 

 between : fig. 1 represents a rough 

 sketch of them. Some local in- 

 formants stated that the promi- 

 nences are called from west to east 

 as shown in the appended sketch ; 

 others that the term Down Cliffs 

 covered the two prominences west 

 of Thorncombe Beacon. The 

 former is the most suitable for 

 distinctive purposes. Down Cliff 

 is not capped by Bridport Sands, 

 but Doghus Cliff is the first 



\one from Seatown which is so 

 capped. Thorncooibe Beacon 

 shows Bridport Sands capped by 

 Greensand ; while Eype Down is below the Junction Bed. 



It may be noted that the cliffs are very fairly accessible even for 

 ladies, with a little practice, though they look formidable. 



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