IN THE ISLE OF PORTLAND AND AROUND WEYMOUTH. 



33 



trace of this interesting deposit in any other of the quarries or 

 sections of the island. The Purbeck beds everywhere present a 

 bare and broken surface. 



The Raised Beach (e, Map and Sections, PL I.). 



This beach extends on the east side of the Bill, exactly one mile 

 from the Sand-holes near Southwell to the " land-mark " at the Bill, 

 and appears to range about a furlong inland, passing under a covering 

 of sand, loam, and rock-debris. From the Bill it extends along the 

 west cliff for a distance of about a quarter of a mile, when it ends 

 against an old subsoil cliff. 



This old beach is most largely developed and thickest on the west 

 side of the Bill ; but it there scarcely contains a shell. It is a mass 

 of well worn and rounded shingle from 5 to 10 feet thick. On the 

 east side, where the coast recedes and was more sheltered from the 

 western gales and drift, the beach is reduced to 3 or 4 feet. 



At the Bill it is only 24 feet above the the present beach. It 

 gradually rises as it trends northward, and is 36 feet above the shore 

 near its north-eastern extremity, and 53 feet at its north-western 

 extremity *. Shells are very numerous at places between Cave Hole 

 and the Sand-holes, but become scarcer on approaching the Bill, 

 and are very rare on the west cliff, where the beach consists of a 

 mass of compact well-rounded shingle, and with little or no sand, 

 whereas on the east side there are also overlying patches, from 

 1 to 3 feet thick, of shelly sand, full of small shells in a beautiful 

 state of preservation, and in places dug out in small holes. At 

 this part of the beach shells are extremely abundant, especially Litto- 

 rina, Patella, Purpura, Ostrea, and Mytilus, and the original 

 colour of the shells is in many cases in great part preserved. On 

 examining the sand I also found it extremely rich in small species, 

 several of which are new to our raised beaches. The following is 

 the list, for which I am indebted to Mr. Gwyn Jeffreys's obliging 

 assistance : — 



Bivalves. 



16. Littorina litorea, L. 



1. Anomia ephippium, Linne. 



17. Rissoa parva, Da Costa ; and yar. 



2. Ostrea edulis, L. 



interrupta, Adams. 



3. Mytilus edulis, L. 



4. Modiola marmorata, Forbes. 



18. striata, Ad. 



19. subcylindrata, Jeffreys, 



5. Cyamium minutum, Fabricius. 



sp. n. 



6. Tellina balthica, L. 



20. Skenea planorbis, Fabr. 



7. Saxicava rugosa, L., yar. arctica. 



21. Purpura la pillus, L. 



22. Buccinum undatum, L. 



Univalves. 



23. Nassa incrassata, Milll. 



8. Patella vulgata, L. 



24. Utriculus truncatulue, Brttguiere. 



9. Tectura virginea, Mutter. 

 10. Trochus helicinus, Fabr. 



FORAMINIFER. 



11. cinerarius, L. 



Miliola seminulum. 



12. umbilicatus, Montagu. 





13. Lacuna portiolus, Ticrton. 



Crustacean. 



14. Littorina obtusata, L. 



Cythere, sp. 



15. rudis, Maton. 





* Measured from top of present beach to top of raised beach. 

 Q. J. G. S. No. 121. d 



