AT ST. ERTH, XE.iR LAND S END, CORNWALL. 



67 



put these specimens into my hands, as "well as some more that he 

 had subsequently procured, and sent me his note-book with the 

 sections, but, to satisfy my inquiry as to the elevation of the bed, 

 visited the spot again, and ran a set of levels from mean tide-mark 

 on the Hayle shore to the pit, by which he ascertained that the 

 elevation of the part from which he obtained his specimens is 98 

 feet above ordnance datum, the surface of the ground being about 

 15 feet higher. 



Fig. 2. — Section across the Valley of the Hayle at St. Erth. 



W.N.W. 



Trecobben Hill. 

 590 feet. 



E.S.E. 



The Hajle 

 Estuary. St. Erth 



Sea-leTel. 



a, a. Ancient rocks. h. Eecent and Prehistoric silt. 



Line shov^ing the probable surface of the sea in the strait in which tlie 



St. Erth shells lived. 



The pits are on the eastern slope of a tract of low ground that 

 extends from Penzance and Marazion on the south coast, to St. Ives 

 Bay on the north coast of the county, cutting off the high ground of 

 the Land's End district from the rest of Cornwall. The bottom of 

 this low tract is occupied by beds of peat and of estuarine or 

 marine silt, altogether unconnected with the bed in question, and 

 which, from the specimens of Mollusca sent to me by ITr. Cornish 

 from some excavations in them, appear to be of that recent date 

 which marks the last depression of Britain * and belongs to the 

 iSTeoKthic period. 



As this tract cuts through the highland formed of ancient rocks, 

 it must at the time of the deposit of the St. Erth beds have been a 

 strait, separating the Land's End region from the mainland of 

 Britain ; but no other indication of this deposit has hitherto been 

 detected. 



[The author here added a provisional list of Mollusca obtained by 

 him to the number of about 50. As this list was confessedly im- 

 perfect, he expressed his intention of preparing and publishing 

 hereafter a full description of the fauna, with figures of the new 

 species; it was withdrawn by him with the permission of the 

 Council,] 



Of the species obtained by me from the bed, three, viz. Cyprcea 

 avellana, Nassa granulata, and Melampus ]pyramidalis, are Eed- 



* The succession of events traced in my memoir on the Newer Pliocene 

 period in England, Q, J. Gr. S, vol. xxxviii. p. 732, terminates j ust prior to this 

 last depression, which is only briefly adverted to, and then only in respect of 

 the amount of depression that has taken place. 



e2 



