1847.] SMITH ON DEPRESSION OF LAND. 237 



tive levels of sea and land, whicli have taken place subsequent to the 

 erection of the building, at which time the ground must have stood at 

 a higher level than it does at present. 



1 . The first movement of which we have evidence is that of gra- 

 dual depression ; this is proved by the false floor which has been 

 placed several feet above the original one. The same process has 

 been necessary in the causeway which connects the church of La Ma- 

 donna del Assunto with the shore ; the sea having washed away a por- 

 tion of the pavement, an older one is exhibited about two feet below. 



2. This has been followed by a period of stationary level, during 

 which the columns were perforated by lithodomous moUusks. 



3. A gradual movement of elevation : this is proved by grants made 

 to the University of Pozzuoli in 1501 and 1503, of the land which 

 the sea was leaving dry (il terreno che il mare andava lasciando in 

 secco), as noticed by Cav. Nicollini. 



4. The paroxysmal elevation in 1538 described in the contemporary 

 accounts. 



5. Lastly, a gradual subsidence, which is still going on at the rate 

 of about one inch yearly. 



The next series of proofs of recent depression belongs to the histo- 

 rical period. The phsenomenon of submerged forests is nowhere 

 more largely developed than on the coasts of Britanny, Normandy 

 and the Channel Islands ; the great rise of tide, amounting in some 

 places to fifty feet, and the flatness of the shores over which it ebbs 

 and flows, in some places not less than seven miles, afford opportuni- 

 ties for observation probably nowhere else to be found. 



The chief peculiarities which distinguish this forest are, first — 



The freshness of the wood. When exposed, the wood does not 

 differ from that of other submerged forests in respect of decay ; such 

 was the case with what I observed in the Bay of St. Ouen in Jersey; 

 but Col. Le Couteur, who lives in that neighbourhood, showed me 

 the stem of an oak, which had been laid bare by a heavy gale, in the 

 most perfect state of preservation. In a communication to the Agri- 

 cultural Society of Jersey, he thus describes it : — " After the gale, 

 which had greatly deimded the sands, I had the good fortune to see 

 the stem of one of these ancient oaks : the trunk stood four feet above 

 the peaty soil on which it was firmly rooted ; its diameter was about 

 three feet. ***** j^ ^ag gi[i\ heart of oak." 



I observed at low water, on the shore between Granville and Avran- 

 ches, stems of oak in the attitude of growth in a similar state of 

 preservation. 



According to the Abbe Manet these ancient stems are locally termed 

 Coerons, and in some places V anaillons ; the wood is used for econo- 

 mical purposes, such as beams in the roofs of houses, furniture, in 

 which its hardness and dark colour give it the polish of ebony, and for 

 espaliers, "qui resistent long temps aux injures de I'air et qui portent 

 avec eux leur peinture," p. 63. 



The next peculiarity which distinguishes these forests is, that they 

 contain the ruins of ancient buildings and works of art. I cannot 



VOL. III. PART I. S 



