Correspondence — Rev. 0. Fisher. 139 



students, who would compare it with the corresponding series on 

 the coast of the mainland. I therefore send you, copied from a 

 rough note-book, an ascending section made by myself in April, 

 1853. I do not vouch for the correctness of the genera named. 

 The date of the observations must be taken as an excuse for errors. 



Ascending section at Hordwell Cliff, goin© fkom Beacon Bunney 



eastwaed. 



Barton Clay. ft. in. 



1. Sandy blue clay, Ancillaria, Uliv^i, Perna, etc 



2. White sand passing into greenish clay with lenticular masses 



of shales. (Searles "Wood gives the following list : i Oliva, 

 Fotamides, Ancillaria, Natica, Sanguinolaria (? Psammobia), 

 Verier icardia, Cytherea, Lucina^ Potamomya) 18 



3. Lignite 4 



4. Green sandy clay with fuci 8 



5. Blue laminated clay abounding in Corbula, Cyrena, Mytilus 



(? Dreissena), and Cerithium 6 



6. Carboniferous clay 1 10 



Fresh-water. 



7. Greenish and bluish sands and clays with Paludina 8 



8. Nodular marly rock 1 



9. Greenish clay (say) 10 



10. Brown sand with stems of fuci 3 6 



11. "White sand passing into clay 4 



12. Grey sand 1 



13. Band of Potamomya , 6 



14. White sand {Crocodile bed) 8 



15. Ferruginous marly nodules 1 



16. Grey clay 4 



17. Limnea marlstone 6 



18. Greenish clay (? Dreissena) 2 6 



19. Band with small Mytilus and Physa 4 



20. Greenish -white clay 7 



21. Yellow sand, small spiral shells, Gyrogonites and black seeds . . 10 



22. Carbonaceous clay 1 



23. Grey sand 1 6 



24. Greenish clay, blue in places, Paludina, Unio 2 



25. Grey sandy clays abounding in vegetable stains 2 6 



Marine. 



26. Sandy foxy clay (seen) 5 



(This corresponds to the "Venus bed,' or Middle Headon.) 



It will be seen from the above section that the calcareous bands 

 (17, etc.) of Hordwell, belonging as they do to the first fresh-water 

 series above the Barton, must be correlated with the Lower Headon 

 Limestones, of which the How Ledge Limestone is the top. They 

 do not repi'esent the Great Upper Headon Limestone. Any correla- 

 tion of the beds of Hordwell Cliff with those of Colwell Bay will 

 therefore be misleading ; the former being below the horizon of the 

 How Ledge Limestone, and the latter above it. The stratum on the 

 mainland which does correspond with the Colwell Bay or Headon 

 Hill "Venus bed," must be sought for at Hordwell above the fresh- 

 water series ; and it occurs at a place called Rook Cliff, about a 

 mile to the east of Beacon Bunney, in a low cliff. It is usually 



1 Charlesworth's Geol. Journ. part 1, p. 4, 1846. 



