202 EEV. J. p. BLAKE ON THJE 



really the most important in this district, is a very distinct deposit, 

 most like the lowest beds at St. Alban's ; only the flints happen to 

 be scarce. The prevailing Ammonites and the Ti^igonice at the base, 

 and the occurrence of the coral permit of no separation palaeonto- 

 logically, and we are forced to regard this as a downward develop- 

 ment of the Portland Stone. Yet it is lithologically a calcareous 

 sandstone, and, if the cementing material be anywhere absent, 

 actually a sand. 



The succeeding rocks in this district have never been described, 

 and thej are with difficulty followed in fields and road- cuttings. 

 The best section is seen in the road leading from the village of 

 Hazelton to the railway, which, confirmed by others, gives us : — 



No. 8. Yellow impure sand becoming marly at the base, often 

 coloured brown by iron ; thickness unknown, but cannot be much 

 more than the maximum seen, viz. 12 feet. No fossils have been 

 seen in it. 



No. 9. Impure calcareous bed, rather rubbly, with large grains 

 of Lydian stone or glauconite, 3 feet 6 inches. Blocks of rock of 

 the same character strewn on the fields have yielded a remarkable 

 fauna to a very short search, viz. Trigonia Pellati, T. variegata, 

 T. concentrica, T. MicJieloti (?), Mytilus jurensis, Perna Bouchai^di, 

 Pecten concentricus (?), Astarte supracorcdlina (?), Eocogyra hruntru- 

 tana, and Serpula sp. Indications of some of these are seen also 

 where the block is in situ. 



No. 10. Harder bed of the same character, 3 feet 6 inches, with 

 Trigonia Pellati, Ostrea hruntrutana, &c. In one spot, on the road 

 from Tisbury to Wardour, this bed is alone seen ; it only reaches 

 18 inches in thickness at most, and is scarcely continuous, but, as 

 it were, in eroded blocks enveloped in the sand above, which is here 

 not so argillaceous. 



No. 11. A yellowish-grey uncompacted calcareous stone, with no 

 fossils seen ; its base is not traceable ; but at a depth of 21 feet from 

 its top the springs break out. These measures are checked by the fact 

 that at the Tisbury station the stone No. 6 is worked in a quarry 

 about 40 feet above the level of the railway, which is on Kimmeridge 

 Clay ; so that that thickness is an upper limit for the intervening 

 beds. 



The character and fossil contents of these beds are different from 

 those of any other locality. The fossils indicate a period anterior 

 to the usual Portland Sand ; indeed they point to an episode similar 

 to the Boulognian. The yellow and hence peroxidized ferruginous 

 sand is very different from the blue sand of the coast sections, and 

 may indicate a more superficial deposit. The diminution and erosion 

 of the hard block No. 10 cannot be much relied on, as the section is 

 not sufficiently removed from surface influences of a later date ; but, 

 on the whole evidence, it appears to me that we have here an area 

 which was elevated previously to the period of the Portland Sand, 

 received its calcareous and shelly accumulations, and then escaped 

 the great deposits of sand which are so alike at Swindon and at 

 Portland, but have here only a representative of a few feet. Prom the 



